1
|
Li Z, Bretscher H, Rao A. Chemical passivation of 2D transition metal dichalcogenides: strategies, mechanisms, and prospects for optoelectronic applications. NANOSCALE 2024; 16:9728-9741. [PMID: 38700268 DOI: 10.1039/d3nr06296a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
The interest in obtaining high-quality monolayer transition metal dichalcogenides (TMDs) for optoelectronic device applications has been growing dramatically. However, the prevalence of defects and unwanted doping in these materials remain challenges, as they both limit optical properties and device performance. Surface chemical treatments of monolayer TMDs have been effective in improving their photoluminescence yield and charge transport properties. In this scenario, a systematic understanding of the underlying mechanism of chemical treatments will lead to a rational design of passivation strategies in future research, ultimately taking a step toward practical optoelectronic applications. We will therefore describe in this mini-review the strategies, progress, mechanisms, and prospects of chemical treatments to passivate and improve the optoelectronic properties of TMDs.
Collapse
Affiliation(s)
- Zhaojun Li
- Solid State Physics, Department of Materials Science and Engineering, Uppsala University, 75103 Uppsala, Sweden.
| | - Hope Bretscher
- The Max Planck Institute for the Structure and Dynamics of Matter, 22761, Hamburg, Germany
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE, Cambridge, UK
| |
Collapse
|
2
|
Harris SB, Biswas A, Yun SJ, Roccapriore KM, Rouleau CM, Puretzky AA, Vasudevan RK, Geohegan DB, Xiao K. Autonomous Synthesis of Thin Film Materials with Pulsed Laser Deposition Enabled by In Situ Spectroscopy and Automation. SMALL METHODS 2024:e2301763. [PMID: 38678523 DOI: 10.1002/smtd.202301763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 04/10/2024] [Indexed: 05/01/2024]
Abstract
Autonomous systems that combine synthesis, characterization, and artificial intelligence can greatly accelerate the discovery and optimization of materials, however platforms for growth of macroscale thin films by physical vapor deposition techniques have lagged far behind others. Here this study demonstrates autonomous synthesis by pulsed laser deposition (PLD), a highly versatile synthesis technique, in the growth of ultrathin WSe2 films. By combing the automation of PLD synthesis and in situ diagnostic feedback with a high-throughput methodology, this study demonstrates a workflow and platform which uses Gaussian process regression and Bayesian optimization to autonomously identify growth regimes for WSe2 films based on Raman spectral criteria by efficiently sampling 0.25% of the chosen 4D parameter space. With throughputs at least 10x faster than traditional PLD workflows, this platform and workflow enables the accelerated discovery and autonomous optimization of the vast number of materials that can be synthesized by PLD.
Collapse
Affiliation(s)
- Sumner B Harris
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Arpan Biswas
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Seok Joon Yun
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Kevin M Roccapriore
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Rama K Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| |
Collapse
|
3
|
Banswar D, Sahu RR, Srivatsava R, Hassan MS, Singh S, Sapra S, Das Gupta T, Goswami A, Balasubramanian K. On the unique temperature-dependent interplay of a B-exciton and its trion in monolayer MoSe 2. NANOSCALE 2024; 16:2632-2641. [PMID: 38227478 DOI: 10.1039/d3nr05677e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
Plasmonics in metal nanoparticles can enhance their near field optical interaction with matter, promoting emission into selected optical modes. Here, using Ga nanoparticles with carefully tuned plasmonic resonance in proximity to MoSe2 monolayers, we show selective photoluminescence enhancement from the B-exciton and its trion with no observable A-exciton emission. The nanoengineered substrate allows for the first direct experimental observation of the B-trion binding energy in semiconducting monolayers. Using temperature-dependent photoluminescence measurements, we show the following features of the MoSe2 B-exciton family: (i) the trion binding energy has an observable temperature dependence with a decreasing trend towards low temperatures and (ii) the exciton-trion emission ratio varies non-monotonically with temperature with a steep increase in the trion emission at lower temperatures. Using detailed models, we identify the particle size required for selective excitation and describe the underlying physical processes. This opens newer avenues for selectively promoting excitonic species and tuning the effective particle lifetimes in monolayer semiconductors. These results demonstrate the excellent plasmonic properties of Ga nanoparticles, which along with facile processing techniques makes it an attractive alternative to the prevalent noble metal plasmonics having applications in flexible/stretchable materials and textiles.
Collapse
Affiliation(s)
- Durgesh Banswar
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India.
| | - Renu Raman Sahu
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India
| | - Rupali Srivatsava
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India.
| | - Md Samim Hassan
- Chemistry Department, Indian Institute of Technology, Delhi, India
| | - Sahil Singh
- Chemistry Department, Indian Institute of Technology, Delhi, India
| | - Sameer Sapra
- Chemistry Department, Indian Institute of Technology, Delhi, India
| | - Tapajyoti Das Gupta
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India
| | - Ankur Goswami
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India.
| | - Krishna Balasubramanian
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India.
| |
Collapse
|
4
|
Li S, Ouyang D, Zhang N, Zhang Y, Murthy A, Li Y, Liu S, Zhai T. Substrate Engineering for Chemical Vapor Deposition Growth of Large-Scale 2D Transition Metal Dichalcogenides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211855. [PMID: 37095721 DOI: 10.1002/adma.202211855] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 04/17/2023] [Indexed: 05/03/2023]
Abstract
The large-scale production of 2D transition metal dichalcogenides (TMDs) is essential to realize their industrial applications. Chemical vapor deposition (CVD) has been considered as a promising method for the controlled growth of high-quality and large-scale 2D TMDs. During a CVD process, the substrate plays a crucial role in anchoring the source materials, promoting the nucleation and stimulating the epitaxial growth. It thus significantly affects the thickness, microstructure, and crystal quality of the products, which are particularly important for obtaining 2D TMDs with expected morphology and size. Here, an insightful review is provided by focusing on the recent development associated with the substrate engineering strategies for CVD preparation of large-scale 2D TMDs. First, the interaction between 2D TMDs and substrates, a key factor for the growth of high-quality materials, is systematically discussed by combining the latest theoretical calculations. Based on this, the effect of various substrate engineering approaches on the growth of large-area 2D TMDs is summarized in detail. Finally, the opportunities and challenges of substrate engineering for the future development of 2D TMDs are discussed. This review might provide deep insight into the controllable growth of high-quality 2D TMDs toward their industrial-scale practical applications.
Collapse
Affiliation(s)
- Shaohua Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Decai Ouyang
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Na Zhang
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Yi Zhang
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Akshay Murthy
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL), Batavia, IL, 60510, USA
| | - Yuan Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
- Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen, 518057, P. R. China
| | - Shiyuan Liu
- State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
- Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen, 518057, P. R. China
| |
Collapse
|
5
|
Sun X, Liu Y, Shi J, Si C, Du J, Liu X, Jiang C, Yang S. Controllable Synthesis of 2H-1T' Mo x Re (1- x ) S 2 Lateral Heterostructures and Their Tunable Optoelectronic Properties. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304171. [PMID: 37278555 DOI: 10.1002/adma.202304171] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/24/2023] [Indexed: 06/07/2023]
Abstract
Constructing heterostructures and doping are valid ways to improve the optoelectronic properties of transition metal dichalcogenides (TMDs) and optimize the performance of TMDs-based photodetectors. Compared with transfer techniques, chemical vapor deposition (CVD) has higher efficiency in preparing heterostructures. As for the one-step CVD growth of heterostructures, cross-contamination between the two materials may occur during the growth process, which may provide the possibility of one-step simultaneous realization of controllable doping and formation of alloy-based heterostructures by finely tuning the growth dynamics. Here, 2H-1T' Mox Re(1- x ) S2 alloy-to-alloy lateral heterostructures are synthesized through this one-step CVD growth method, utilizing the cross-contamination and different growth temperatures of the two alloys. Due to the doping of a small amount of Re atoms in 2H MoS2 , 2H Mox Re(1- x ) S2 has a high response rejection ratio in the solar-blind ultraviolet (SBUV) region and exhibits a positive photoconductive (PPC) effect. While the 1T' Mox Re(1- x ) S2 formed by heavily doping Mo atoms into 1T' ReS2 will produce a negative photoconductivity (NPC) effect under UV laser irradiation. The optoelectronic property of 2H-1T' Mox Re(1- x ) S2 -based heterostructures can be modulated by gate voltage. These findings are expected to expand the functionality of traditional optoelectronic devices and have potential applications in optoelectronic logic devices.
Collapse
Affiliation(s)
- Xiaona Sun
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Yang Liu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Jianwei Shi
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Chen Si
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Jiantao Du
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Xinfeng Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Chengbao Jiang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| | - Shengxue Yang
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, P. R. China
| |
Collapse
|
6
|
Bui MN, Rost S, Auge M, Zhou L, Friedrich C, Blügel S, Kretschmer S, Krasheninnikov AV, Watanabe K, Taniguchi T, Hofsäss HC, Grützmacher D, Kardynał BE. Optical Properties of MoSe 2 Monolayer Implanted with Ultra-Low-Energy Cr Ions. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37432886 PMCID: PMC10375475 DOI: 10.1021/acsami.3c05366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
This paper explores the optical properties of an exfoliated MoSe2 monolayer implanted with Cr+ ions, accelerated to 25 eV. Photoluminescence of the implanted MoSe2 reveals an emission line from Cr-related defects that is present only under weak electron doping. Unlike band-to-band transition, the Cr-introduced emission is characterized by nonzero activation energy, long lifetimes, and weak response to the magnetic field. To rationalize the experimental results and get insights into the atomic structure of the defects, we modeled the Cr-ion irradiation process using ab initio molecular dynamics simulations followed by the electronic structure calculations of the system with defects. The experimental and theoretical results suggest that the recombination of electrons on the acceptors, which could be introduced by the Cr implantation-induced defects, with the valence band holes is the most likely origin of the low-energy emission. Our results demonstrate the potential of low-energy ion implantation as a tool to tailor the properties of two-dimensional (2D) materials by doping.
Collapse
Affiliation(s)
- Minh N Bui
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Stefan Rost
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute 1 (PGI-1) and Institute for Advanced Simulation 1 (IAS-1), Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - Manuel Auge
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Lanqing Zhou
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | | | - Stefan Blügel
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Silvan Kretschmer
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Arkady V Krasheninnikov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, 00076 Aalto, Finland
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Hans C Hofsäss
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Beata E Kardynał
- Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
| |
Collapse
|
7
|
Li Z, Ma X, Pan H, Chu H, Pan Z, Li Y, Zhao S, Li D. Optical absorption of bismuthene with a single vacancy: first-principle calculations. OPTICS EXPRESS 2023; 31:19666-19674. [PMID: 37381377 DOI: 10.1364/oe.493962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/17/2023] [Indexed: 06/30/2023]
Abstract
The exceptional mechanical, electronic, topological, and optical properties, make bismuthene an ideal candidate for various applications in ultrafast saturation absorption and spintronics. Despite the extensive research efforts devoted to synthesizing this material, the introduction of defects, which can significantly affect its properties, remains a substantial obstacle. In this study, we investigate the transition dipole moment and joint density of states of bismuthene with/without single vacancy defect via energy band theory and interband transition theory. It is demonstrated that the existence of the single defect enhances the dipole transition and joint density of states at lower photon energies, ultimately resulting in an additional absorption peak in the absorption spectrum. Our results suggest that the manipulation of defects in bismuthene has enormous potential for improving the optoelectronic properties of this material.
Collapse
|
8
|
Gupta JD, Jangra P, Majee BP, Mishra AK. Morphological dependent exciton dynamics and thermal transport in MoSe 2 films. NANOSCALE ADVANCES 2023; 5:2756-2766. [PMID: 37205289 PMCID: PMC10187041 DOI: 10.1039/d3na00164d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 04/11/2023] [Indexed: 05/21/2023]
Abstract
Thermal transport and exciton dynamics of semiconducting transition metal dichalcogenides (TMDCs) play an immense role in next-generation electronic, photonic, and thermoelectric devices. In this work, we synthesize distinct morphologies (snow-like and hexagonal) of a trilayer MoSe2 film over the SiO2/Si substrate via the chemical vapor deposition (CVD) method and investigated their morphological dependent exciton dynamics and thermal transport behaviour for the first time to the best of our knowledge. Firstly, we studied the role of spin-orbit and interlayer couplings both theoretically as well as experimentally via first-principles density functional theory and photoluminescence study, respectively. Further, we demonstrate morphological dependent thermal sensitive exciton response at low temperatures (93-300 K), showing more dominant defect-bound excitons (EL) in snow-like MoSe2 compared to hexagonal morphology. We also examined the morphological-dependent phonon confinement and thermal transport behaviour using the optothermal Raman spectroscopy technique. To provide insights into the nonlinear temperature-dependent phonon anharmonicity, a semi-quantitative model comprising volume and temperature effects was used, divulging the dominance of three-phonon (four-phonon) scattering processes for thermal transport in hexagonal (snow-like) MoSe2. The morphological impact on thermal conductivity (ks) of MoSe2 has also been examined here by performing the optothermal Raman spectroscopy, showing ks ∼ 36 ± 6 W m-1 K-1 for snow-like and ∼41 ± 7 W m-1 K-1 for hexagonal MoSe2. Our research will contribute to the understanding of thermal transport behaviour in different morphologies of semiconducting MoSe2, finding suitability for next-generation optoelectronic devices.
Collapse
Affiliation(s)
- Jay Deep Gupta
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi-221005 India
| | - Priyanka Jangra
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi-221005 India
| | - Bishnu Pada Majee
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi-221005 India
| | - Ashish Kumar Mishra
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi-221005 India
| |
Collapse
|
9
|
Zhong J, Zhang X, He W, Gong D, Lan M, Dai X, Peng Y, Xiang G. Large-scale fabrication and Mo vacancy-induced robust room-temperature ferromagnetism of MoSe 2 thin films. NANOSCALE 2023; 15:6844-6852. [PMID: 36961230 DOI: 10.1039/d3nr00207a] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Molybdenum selenide (MoSe2) has recently attracted particular attention due to its room-temperature ferromagnetism (RTFM) and related spintronic applications. However, not only does the FM mechanism of MoSe2 remain controversial, but also the synthesis of MoSe2 thin films with robust RTFM is still an unmet challenge. Here it is shown that using polymer-assisted deposition under appropriate growth conditions, large-scale (4 cm × 4 cm) synthesis of MoSe2 thin films with robust RTFM and a smooth surface (roughness average ∼0.22 nm) is possible. A new record-high saturation magnetization (6.69 emu g-1) is achieved in the prepared MoSe2 thin films, about 5 times the previously reported record (1.39 emu g-1) obtained in 2H-MoSe2 nanoflakes. Meanwhile, the coercivity of the MoSe2 films can be tuned down to a new record-low value (5.0 Oe), one-tenth of the previously reported record. Notably, detailed analysis combining the experimental findings and calculation results shows that the robust RTFM mainly comes from the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction between the magnetic moments induced by abundant Mo vacancies (VMos) in the MoSe2 films. Our results give insights into the large-scale production and robust RTFM of MoSe2 thin films and may provide a platform for designing and fabricating spintronic materials and devices based on transition-metal dichalcogenides.
Collapse
Affiliation(s)
- Jing Zhong
- College of Physics, Sichuan University, Chengdu 610064, China.
| | - Xi Zhang
- College of Physics, Sichuan University, Chengdu 610064, China.
| | - Wa He
- College of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Dan Gong
- College of Physics, Sichuan University, Chengdu 610064, China.
| | - Mu Lan
- College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China
| | - Xu Dai
- College of Physics, Sichuan University, Chengdu 610064, China.
| | - Yong Peng
- College of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Gang Xiang
- College of Physics, Sichuan University, Chengdu 610064, China.
| |
Collapse
|
10
|
Bala A, So B, Pujar P, Moon C, Kim S. In Situ Synthesis of Two-Dimensional Lateral Semiconducting-Mo:Se//Metallic-Mo Junctions Using Controlled Diffusion of Se for High-Performance Large-Scaled Memristor. ACS NANO 2023; 17:4296-4305. [PMID: 36606582 DOI: 10.1021/acsnano.2c08615] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) materials are favorable candidates for resistive memories in high-density nanoelectronics owing to their ultrathin scaling and controllable interfacial characteristics. However, high processing temperatures and difficulties in mechanical transfer are intriguing challenges associated with their implementation in large areas with crossbar architecture. A high processing temperature may damage the electrical functionalities of the bottom electrode, and mechanical transfer of 2D materials may introduce undesirable microscopic defects and macroscopic discontinuities. In this study, an in situ fabrication of an electrode and 2D-molybdenum diselenide (MoSe2) is reported. The controlled diffusion of selenium (Se) in the predeposited molybdenum (Mo) produces Mo//Mo:Se stacks with a few layers of MoSe2 on top and MoSex on the bottom. Diffusion-assisted Mo//Mo:Se fabrication is observed over a large area (4 in. wafer). Additionally, a 5 × 5 array of crossbar memristors (Mo//Mo:Se//Ag) is fabricated using the diffusion of Se in patterned Mo. These memristors exhibit a small switching voltage (∼1.1 V), high endurance (>250 cycles), and excellent retention (>15 000 s) with minimum cycle-to-cycle and device-to-device variation. Thus, the proposed nondestructive in situ technique not only simplifies the fabrication but also minimizes the number of required stages.
Collapse
Affiliation(s)
- Arindam Bala
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon16419, Republic of Korea
| | - Byungjun So
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon16419, Republic of Korea
| | - Pavan Pujar
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon16419, Republic of Korea
| | - Changgyun Moon
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon16419, Republic of Korea
| | - Sunkook Kim
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon16419, Republic of Korea
| |
Collapse
|
11
|
Liu F, Fan Z. Defect engineering of two-dimensional materials for advanced energy conversion and storage. Chem Soc Rev 2023; 52:1723-1772. [PMID: 36779475 DOI: 10.1039/d2cs00931e] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
In the global trend towards carbon neutrality, sustainable energy conversion and storage technologies are of vital significance to tackle the energy crisis and climate change. However, traditional electrode materials gradually reach their property limits. Two-dimensional (2D) materials featuring large aspect ratios and tunable surface properties exhibit tremendous potential for improving the performance of energy conversion and storage devices. To rationally control the physical and chemical properties for specific applications, defect engineering of 2D materials has been investigated extensively, and is becoming a versatile strategy to promote the electrode reaction kinetics. Simultaneously, exploring the in-depth mechanisms underlying defect action in electrode reactions is crucial to provide profound insight into structure tailoring and property optimization. In this review, we highlight the cutting-edge advances in defect engineering in 2D materials as well as their considerable effects in energy-related applications. Moreover, the confronting challenges and promising directions are discussed for the development of advanced energy conversion and storage systems.
Collapse
Affiliation(s)
- Fu Liu
- Department of Chemistry, City University of Hong Kong, Hong Kong 999077, China.
| | - Zhanxi Fan
- Department of Chemistry, City University of Hong Kong, Hong Kong 999077, China. .,Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Hong Kong 999077, China.,Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
| |
Collapse
|
12
|
Selhorst R, Yu Z, Moore D, Jiang J, Susner MA, Glavin NR, Pachter R, Terrones M, Maruyama B, Rao R. Precision Modification of Monolayer Transition Metal Dichalcogenides via Environmental E-Beam Patterning. ACS NANO 2023; 17:2958-2967. [PMID: 36689725 DOI: 10.1021/acsnano.2c11503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Layered Transition Metal Dichalcogenides (TMDs) are an important class of materials that exhibit a wide variety of optoelectronic properties. The ability to spatially tailor their expansive property-space (e.g., conduction behavior, optical emission, surface interactions) is of special interest for applications including, but not limited to, sensing, bioelectronics, and spintronics/valleytronics. Current methods of property modulation focus on the modification of the basal surfaces and edge sites of the TMDs by the introduction of defects, functionalization with organic or inorganic moieties, alloying, heterostructure formation, and phase engineering. A majority of these methods lack the resolution for the development of next-generation nanoscale devices or are limited in the types of functionalities useful for efficient TMD property modification. In this study, we utilize electron-beam patterning on monolayer TMDs (MoSe2, WSe2 and MoS2) in the presence of a pressure-controlled atmosphere of water vapor within an environmental scanning electron microscope (ESEM). A series of parametric studies show local optical and electronic property modification depending on acceleration voltage, beam current, pressure, and electron dose. The ultimate pattern resolution achieved is 67 ± 9 nm. Raman and photoluminescence spectroscopies coupled with Kelvin Probe Force Microscopy reveal electron dose-dependent p-doping in the patterned regions, which we attribute to functionalization from the products of water vapor radiolysis (oxygen and hydroxyl groups). The modulation of the work function through patterning matches well with Density Functional Theory modeling. Finally, post-functionalization of the patterned areas with an organic fluorophore demonstrates a robust method to achieve nanoscale functionalization with high fidelity.
Collapse
Affiliation(s)
- Ryan Selhorst
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
- UES Inc., 4401 Dayton-Xenia Rd., Dayton, Ohio 45433, United States
| | - Zhuohang Yu
- Department of Materials Science and Engineering, The Pennsylvania State University, 221 Steidle Building, University Park, Pennsylvania 16802, United States
| | - David Moore
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Jie Jiang
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Michael A Susner
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Nicholas R Glavin
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Ruth Pachter
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Mauricio Terrones
- Department of Materials Science and Engineering, The Pennsylvania State University, 221 Steidle Building, University Park, Pennsylvania 16802, United States
| | - Benji Maruyama
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Rahul Rao
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 2179 12th Street, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States
| |
Collapse
|
13
|
Maurya PK, Mishra S, Mishra AK. MoSe2 and NiCo2O4/NiO Based Hybrid Nanostructure as Novel Electrocatalyst for High Performance Rechargeable Zinc-Air Battery. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
14
|
Bangar H, Kumar A, Chowdhury N, Mudgal R, Gupta P, Yadav RS, Das S, Muduli PK. Large Spin-To-Charge Conversion at the Two-Dimensional Interface of Transition-Metal Dichalcogenides and Permalloy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:41598-41604. [PMID: 36052925 DOI: 10.1021/acsami.2c11162] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Spin-to-charge conversion is an essential requirement for the implementation of spintronic devices. Recently, monolayers (MLs) of semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable interest for spin-to-charge conversion due to their high spin-orbit coupling and lack of inversion symmetry in their crystal structure. However, reports of direct measurement of spin-to-charge conversion at TMD-based interfaces are very much limited. Here, we report on the room-temperature observation of a large spin-to-charge conversion arising from the interface of Ni80Fe20 (Py) and four distinct large-area (∼5 × 2 mm2) ML TMDs, namely, MoS2, MoSe2, WS2, and WSe2. We show that both spin mixing conductance and the Rashba efficiency parameter (λIREE) scale with the spin-orbit coupling strength of the ML TMD layers. The λIREE parameter is found to range between -0.54 and -0.76 nm for the four ML TMDs, demonstrating a large spin-to-charge conversion. Our findings reveal that the TMD/ferromagnet interface can be used for efficient generation and detection of spin current, opening new opportunities for novel spintronic devices.
Collapse
Affiliation(s)
- Himanshu Bangar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Akash Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
| | - Niru Chowdhury
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Richa Mudgal
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pankhuri Gupta
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Samaresh Das
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| |
Collapse
|
15
|
Kirubasankar B, Won YS, Adofo LA, Choi SH, Kim SM, Kim KK. Atomic and structural modifications of two-dimensional transition metal dichalcogenides for various advanced applications. Chem Sci 2022; 13:7707-7738. [PMID: 35865881 PMCID: PMC9258346 DOI: 10.1039/d2sc01398c] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/18/2022] [Indexed: 12/14/2022] Open
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDs) and their heterostructures have attracted significant interest in both academia and industry because of their unusual physical and chemical properties. They offer numerous applications, such as electronic, optoelectronic, and spintronic devices, in addition to energy storage and conversion. Atomic and structural modifications of van der Waals layered materials are required to achieve unique and versatile properties for advanced applications. This review presents a discussion on the atomic-scale and structural modifications of 2D TMDs and their heterostructures via post-treatment. Atomic-scale modifications such as vacancy generation, substitutional doping, functionalization and repair of 2D TMDs and structural modifications including phase transitions and construction of heterostructures are discussed. Such modifications on the physical and chemical properties of 2D TMDs enable the development of various advanced applications including electronic and optoelectronic devices, sensing, catalysis, nanogenerators, and memory and neuromorphic devices. Finally, the challenges and prospects of various post-treatment techniques and related future advanced applications are addressed.
Collapse
Affiliation(s)
- Balakrishnan Kirubasankar
- Department of Energy Science, Sungkyunkwan University Suwon 16419 South Korea .,Department of Chemistry, Sookmyung Women's University Seoul 14072 South Korea
| | - Yo Seob Won
- Department of Energy Science, Sungkyunkwan University Suwon 16419 South Korea .,Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University Suwon 16419 South Korea
| | - Laud Anim Adofo
- Department of Energy Science, Sungkyunkwan University Suwon 16419 South Korea .,Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University Suwon 16419 South Korea
| | - Soo Ho Choi
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University Suwon 16419 South Korea
| | - Soo Min Kim
- Department of Chemistry, Sookmyung Women's University Seoul 14072 South Korea
| | - Ki Kang Kim
- Department of Energy Science, Sungkyunkwan University Suwon 16419 South Korea .,Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University Suwon 16419 South Korea
| |
Collapse
|
16
|
Xiao K, Geohegan DB. Laser synthesis and processing of atomically thin 2D materials. TRENDS IN CHEMISTRY 2022. [DOI: 10.1016/j.trechm.2022.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
17
|
Xue Y, Shao P, Lin M, Yuan Y, Shi W, Cui F. Tailoring S-vacancy concentration changes the type of the defect and photocatalytic activity in ZFS. JOURNAL OF HAZARDOUS MATERIALS 2022; 428:128215. [PMID: 35033917 DOI: 10.1016/j.jhazmat.2022.128215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/06/2021] [Accepted: 01/02/2022] [Indexed: 06/14/2023]
Abstract
Defect engineering is crucial in the development of semiconductor catalyst activity. However, the influence of defect/vacancy density and states on catalysis remains vague. Thus, the optimized sulfur vacancy (SV) state is achieved among Fe-ZnS models (ZFS) via a chemical etching strategy for photocatalytic degradation (PD). As the SV concentration (ρSV) increases, the predominant state of vacancies changes from isolated defects-a state to a combination of a state and vacancy clusters-e state, as verified by positron annihilation and X-ray absorption fine structure spectra. However, the two types of defect states activated the intrinsic activity of the crystal via radically different mechanisms and exerted different degrees of influence on PD activity, as revealed by first-principles calculations and quantitative structure-activity relationship. Our results suggest that the SV activity is strongly influenced by its concentration in the ZFS crystal, while the vacancy concentration is not a control parameter for the PD activity, but a defect form. The underlying essence of atomic defects behavior affecting crystal catalytic activity at the atomic level is also revealed in this paper. Uncovering these structural relationships provide a theoretical basis for designing effective catalysts.
Collapse
Affiliation(s)
- Yanei Xue
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Penghui Shao
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Mingli Lin
- China Academy of Urban Planning and Design, Beijing 100000, PR China
| | - Yixing Yuan
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Wenxin Shi
- College of Environment and Ecology, Chongqing University, Chongqing 400044, PR China
| | - Fuyi Cui
- College of Environment and Ecology, Chongqing University, Chongqing 400044, PR China
| |
Collapse
|
18
|
Cavallini M, Gentili D. Atomic Vacancies in Transition Metal Dichalcogenides: Properties, Fabrication, and Limits. Chempluschem 2022; 87:e202100562. [PMID: 35312184 DOI: 10.1002/cplu.202100562] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/03/2022] [Indexed: 11/11/2022]
Abstract
Structural defects, such as heteroatoms or atomic vacancies, are always present in materials and significantly affect their physical properties, in both positive or unwanted ways. Interestingly, defects generate an impressive range of functionalities in many materials, such as catalysis, electrical and thermal conductivity tuning, thermoelectricity, enhanced ion storage, magnetism, and others. These properties enable the use of defective materials in a great variety of technological applications. Here we review the principal properties generated by atomic vacancies in 2D compounds and thin films of transition metal dichalcogenides and the most consolidated methods for their formation and engineering. Eventually, we critically analysed the most important advantages, the limits and the current open challenges.
Collapse
Affiliation(s)
- Massimiliano Cavallini
- Istituto per lo Studio dei Materiali Nanostrutturati, (ISMN), Consiglio Nazionale delle Ricerche (CNR), Via P.Gobetti 101, Bologna, Italy
| | - Denis Gentili
- Istituto per lo Studio dei Materiali Nanostrutturati, (ISMN), Consiglio Nazionale delle Ricerche (CNR), Via P.Gobetti 101, Bologna, Italy
| |
Collapse
|
19
|
Di Bernardo I, Blyth J, Watson L, Xing K, Chen YH, Chen SY, Edmonds MT, Fuhrer MS. Defects, band bending and ionization rings in MoS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:174002. [PMID: 35081526 DOI: 10.1088/1361-648x/ac4f1d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Chalcogen vacancies in transition metal dichalcogenides are widely acknowledged as both donor dopants and as a source of disorder. The electronic structure of sulphur vacancies in MoS2however is still controversial, with discrepancies in the literature pertaining to the origin of the in-gap features observed via scanning tunneling spectroscopy (STS) on single sulphur vacancies. Here we use a combination of scanning tunnelling microscopy and STS to study embedded sulphur vacancies in bulk MoS2crystals. We observe spectroscopic features dispersing in real space and in energy, which we interpret as tip position- and bias-dependent ionization of the sulphur vacancy donor due to tip induced band bending. The observations indicate that care must be taken in interpreting defect spectra as reflecting in-gap density of states, and may explain discrepancies in the literature.
Collapse
Affiliation(s)
- Iolanda Di Bernardo
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - James Blyth
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Liam Watson
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Kaijian Xing
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Yi-Hsun Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Shao-Yu Chen
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
| | - Mark T Edmonds
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
| | - Michael S Fuhrer
- Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, 3800, VIC, Australia
- School of Physics and Astronomy, Monash University, Clayton, 3800, VIC, Australia
- Monash Centre for Atomically Thin Materials, Monash University, Clayton, 3800, VIC, Australia
| |
Collapse
|
20
|
Ko W, Gai Z, Puretzky AA, Liang L, Berlijn T, Hachtel JA, Xiao K, Ganesh P, Yoon M, Li AP. Understanding Heterogeneities in Quantum Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2106909. [PMID: 35170112 DOI: 10.1002/adma.202106909] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Quantum materials are usually heterogeneous, with structural defects, impurities, surfaces, edges, interfaces, and disorder. These heterogeneities are sometimes viewed as liabilities within conventional systems; however, their electronic and magnetic structures often define and affect the quantum phenomena such as coherence, interaction, entanglement, and topological effects in the host system. Therefore, a critical need is to understand the roles of heterogeneities in order to endow materials with new quantum functions for energy and quantum information science applications. In this article, several representative examples are reviewed on the recent progress in connecting the heterogeneities to the quantum behaviors of real materials. Specifically, three intertwined topic areas are assessed: i) Reveal the structural, electronic, magnetic, vibrational, and optical degrees of freedom of heterogeneities. ii) Understand the effect of heterogeneities on the behaviors of quantum states in host material systems. iii) Control heterogeneities for new quantum functions. This progress is achieved by establishing the atomistic-level structure-property relationships associated with heterogeneities in quantum materials. The understanding of the interactions between electronic, magnetic, photonic, and vibrational states of heterogeneities enables the design of new quantum materials, including topological matter and quantum light emitters based on heterogenous 2D materials.
Collapse
Affiliation(s)
- Wonhee Ko
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Liangbo Liang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Tom Berlijn
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Jordan A Hachtel
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Mina Yoon
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - An-Ping Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| |
Collapse
|
21
|
Kim HJ, Van Quang N, Nguyen TH, Kim S, Lee Y, Lee IH, Cho S, Seong MJ, Kim K, Chang YJ. Tuning of Thermoelectric Properties of MoSe 2 Thin Films Under Helium Ion Irradiation. NANOSCALE RESEARCH LETTERS 2022; 17:26. [PMID: 35142901 PMCID: PMC8831667 DOI: 10.1186/s11671-022-03665-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/30/2022] [Indexed: 06/14/2023]
Abstract
Transition metal dichalcogenides have attracted renewed interest for use as thermoelectric materials owing to their tunable bandgap, moderate Seebeck coefficient, and low thermal conductivity. However, their thermoelectric parameters such as Seebeck coefficient, electrical conductivity, and thermal conductivity are interdependent, which is a drawback. Therefore, it is necessary to find a way to adjust one of these parameters without affecting the other parameters. In this study, we investigated the effect of helium ion irradiation on MoSe2 thin films with the objective of controlling the Seebeck coefficient and electrical conductivity. At the optimal irradiation dose of 1015 cm-2, we observed multiple enhancements of the power factor resulting from an increase in the electrical conductivity, with slight suppression of the Seebeck coefficient. Raman spectroscopy, X-ray diffraction, and transmission electron microscopy analyses revealed that irradiation-induced selenium vacancies played an important role in changing the thermoelectric properties of MoSe2 thin films. These results suggest that helium ion irradiation is a promising method to significantly improve the thermoelectric properties of two-dimensional transition metal dichalcogenides. Effect of He+ irradiation on thermoelectric properties of MoSe2 thin films.
Collapse
Affiliation(s)
- Hyuk Jin Kim
- Department of Physics, University of Seoul, 163 Siripdaero, Dongdaemun-gu, Bldg 14-217, Seoul, 02504 Republic of Korea
| | - Nguyen Van Quang
- Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan, 44610 Republic of Korea
| | - Thi Huong Nguyen
- Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan, 44610 Republic of Korea
| | - Sera Kim
- Department of Physics, Chung-Ang University, Seoul, 06974 Republic of Korea
| | - Yangjin Lee
- Department of Physics, Yonsei University, Seoul, 03722 Republic of Korea
| | - In Hak Lee
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792 Republic of Korea
| | - Sunglae Cho
- Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan, 44610 Republic of Korea
| | - Maeng-Je Seong
- Department of Physics, Chung-Ang University, Seoul, 06974 Republic of Korea
| | - Kwanpyo Kim
- Department of Physics, Yonsei University, Seoul, 03722 Republic of Korea
| | - Young Jun Chang
- Department of Physics, University of Seoul, 163 Siripdaero, Dongdaemun-gu, Bldg 14-217, Seoul, 02504 Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504 Republic of Korea
| |
Collapse
|
22
|
Konar R, Rajeswaran B, Paul A, Teblum E, Aviv H, Perelshtein I, Grinberg I, Tischler YR, Nessim GD. CVD-Assisted Synthesis of 2D Layered MoSe 2 on Mo Foil and Low Frequency Raman Scattering of Its Exfoliated Few-Layer Nanosheets on CaF 2 Substrates. ACS OMEGA 2022; 7:4121-4134. [PMID: 35155906 PMCID: PMC8829917 DOI: 10.1021/acsomega.1c05652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 01/04/2022] [Indexed: 06/14/2023]
Abstract
Transition-metal dichalcogenides (TMDCs) are unique layered materials with exotic properties. So, examining their structures holds tremendous importance. 2H-MoSe2 (analogous to MoS2; Gr. 6 TMDC) is a crucial optoelectronic material studied extensively using Raman spectroscopy. In this regard, low-frequency Raman (LFR) spectroscopy can probe this material's structure as it reveals distinct vibration modes. Here, we focus on understanding the microstructural evolution of different 2H-MoSe2 morphologies and their layers using LFR scattering. We grew phase-pure 2H-MoSe2 (with variable microstructures) directly on a Mo foil using a two-furnace ambient-pressure chemical vapor deposition (CVD) system by carefully controlling the process parameters. We analyzed the layers of exfoliated flakes after ultrasonication and drop-cast 2H-MoSe2 of different layer thicknesses by choosing different concentrations of 2H-MoSe2 solutions. Further detailed analyses of the respective LFR regions confirm the presence of newly identified Raman signals for the 2H-MoSe2 nanosheets drop-cast on Raman-grade CaF2. Our results show that CaF2 is an appropriate Raman-enhancing substrate compared to Si/SiO2 as it presents new LFR modes of 2H-MoSe2. Therefore, CaF2 substrates are a promising medium to characterize in detail other TMDCs using LFR spectroscopy.
Collapse
|
23
|
Lee Y, Chang S, Chen S, Chen S, Chen H. Optical Inspection of 2D Materials: From Mechanical Exfoliation to Wafer-Scale Growth and Beyond. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2102128. [PMID: 34716758 PMCID: PMC8728831 DOI: 10.1002/advs.202102128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/13/2021] [Indexed: 05/11/2023]
Abstract
Optical inspection is a rapid and non-destructive method for characterizing the properties of two-dimensional (2D) materials. With the aid of optical inspection, in situ and scalable monitoring of the properties of 2D materials can be implemented industrially to advance the development and progress of 2D material-based devices toward mass production. This review discusses the optical inspection techniques that are available to characterize various 2D materials, including graphene, transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), group-III monochalcogenides, black phosphorus (BP), and group-IV monochalcogenides. First, the authors provide an introduction to these 2D materials and the processes commonly used for their fabrication. Then they review several of the important structural properties of 2D materials, and discuss how to characterize them using appropriate optical inspection tools. The authors also describe the challenges and opportunities faced when applying optical inspection to recently developed 2D materials, from mechanically exfoliated to wafer-scale-grown 2D materials. Most importantly, the authors summarize the techniques available for largely and precisely enhancing the optical signals from 2D materials. This comprehensive review of the current status and perspective of future trends for optical inspection of the structural properties of 2D materials will facilitate the development of next-generation 2D material-based devices.
Collapse
Affiliation(s)
- Yang‐Chun Lee
- Department of Materials Science and EngineeringNational Taiwan UniversityNo. 1, Sec. 4, Roosevelt RoadTaipei10617Taiwan
| | - Sih‐Wei Chang
- Department of Materials Science and EngineeringNational Taiwan UniversityNo. 1, Sec. 4, Roosevelt RoadTaipei10617Taiwan
| | - Shu‐Hsien Chen
- Department of Materials Science and EngineeringNational Taiwan UniversityNo. 1, Sec. 4, Roosevelt RoadTaipei10617Taiwan
| | - Shau‐Liang Chen
- Department of Materials Science and EngineeringNational Taiwan UniversityNo. 1, Sec. 4, Roosevelt RoadTaipei10617Taiwan
| | - Hsuen‐Li Chen
- Department of Materials Science and EngineeringNational Taiwan UniversityNo. 1, Sec. 4, Roosevelt RoadTaipei10617Taiwan
| |
Collapse
|
24
|
Zhang X, Zhang X, Ajayan PM, Wen J, Espinosa HD. Edge-Mediated Annihilation of Vacancy Clusters in Monolayer Molybdenum Diselenide (MoSe 2 ) under Electron Beam Irradiation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2105194. [PMID: 34783451 DOI: 10.1002/smll.202105194] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Annihilation of vacancy clusters in monolayer molybdenum diselenide (MoSe2 ) under electron beam irradiation is reported. In situ high-resolution transmission electron microscopy observation reveals that the annihilation is achieved by diffusion of vacancies to the free edge near the vacancy clusters. Monte Carlo simulations confirm that it is energetically favorable for the vacancies to locate at the free edge. By computing the minimum energy path for the annihilation of one vacancy cluster as a case study, it is further shown that electron beam irradiation and pre-stress in the suspended MoSe2 monolayer are necessary for the vacancies to overcome the energy barriers for diffusion. The findings suggest a new mechanism of vacancy healing in 2D materials and broaden the capability of electron beam for defect engineering of 2D materials, a promising way of tuning their properties for engineering applications.
Collapse
Affiliation(s)
- Xu Zhang
- Theoretical and Applied Mechanics Program, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Xiang Zhang
- Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Pulickel M Ajayan
- Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Jianguo Wen
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Horacio D Espinosa
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| |
Collapse
|
25
|
Wang K, Zhang L, Nguyen GD, Sang X, Liu C, Yu Y, Ko W, Unocic RR, Puretzky AA, Rouleau CM, Geohegan DB, Fu L, Duscher G, Li AP, Yoon M, Xiao K. Selective Antisite Defect Formation in WS 2 Monolayers via Reactive Growth on Dilute W-Au Alloy Substrates. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106674. [PMID: 34738669 DOI: 10.1002/adma.202106674] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Defects are ubiquitous in 2D materials and can affect the structure and properties of the materials and also introduce new functionalities. Methods to adjust the structure and density of defects during bottom-up synthesis are required to control the growth of 2D materials with tailored optical and electronic properties. Here, the authors present an Au-assisted chemical vapor deposition approach to selectively form SW and S2W antisite defects, whereby one or two sulfur atoms substitute for a tungsten atom in WS2 monolayers. Guided by first-principles calculations, they describe a new method that can maintain tungsten-poor growth conditions relative to sulfur via the low solubility of W atoms in a gold/W alloy, thereby significantly reducing the formation energy of the antisite defects during the growth of WS2 . The atomic structure and composition of the antisite defects are unambiguously identified by Z-contrast scanning transmission electron microscopy and electron energy-loss spectroscopy, and their total concentration is statistically determined, with levels up to ≈5.0%. Scanning tunneling microscopy/spectroscopy measurements and first-principles calculations further verified these antisite defects and revealed the localized defect states in the bandgap of WS2 monolayers. This bottom-up synthesis method to form antisite defects should apply in the synthesis of other 2D materials.
Collapse
Affiliation(s)
- Kai Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Lizhi Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37916, USA
| | - Giang D Nguyen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Xiahan Sang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070, China
- Nanostructure Research Centre, Wuhan University of Technology, Luoshi Road 122, Wuhan, 430070, China
| | - Chenze Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yiling Yu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Wonhee Ko
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Raymond R Unocic
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Lei Fu
- College of Chemistry and Molecular Science, Wuhan University, Wuhan, 430072, China
| | - Gerd Duscher
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37916, USA
| | - An-Ping Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Mina Yoon
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| |
Collapse
|
26
|
Tursun M, Wu C. Vacancy-triggered and dopant-assisted NO electrocatalytic reduction over MoS 2. Phys Chem Chem Phys 2021; 23:19872-19883. [PMID: 34525138 DOI: 10.1039/d1cp02764f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Nitric oxide electroreduction reaction (NOER) is an efficient method for NH3 synthesis and NOx-related pollutant treatment. However, current research on NOER catalysts mainly focuses on noble metals and single atom catalysts, while low-cost transition metal dichalcogenides (TMDCs) are rarely considered. Herein, by applying density functional theory (DFT) calculations, we study the catalytic performance of NOER over 2H-MoS2 monolayers with the most common S vacancies and some Mo atoms substituted by transition metal atoms (denoted as TM-MoS2@VS). Our results show that an S vacancy and a heteroatom substitution tend to form a first nearest neighbour (1NN) pair, which greatly improves the NOER catalytic performance of 2H-MoS2. The S vacancy site can trigger NOER by strongly adsorbing a NO molecule and elongating the NO bond, while the heteroatom dopant can assist NOER by tuning the electron donating capability of 2H-MoS2 which breaks the linear scaling relations among key reaction intermediates. At low NO coverage, NH3 can be correspondingly yielded at -0.06 and -0.38 V onset potentials over the Pt- and Au-doped MoS2 catalysts with S vacancies (Pt-MoS2@VS and Au-MoS2@VS). At high NO coverage, N2O/N2 is thermodynamically favored. Meanwhile, the competing hydrogen evolution reaction (HER) is suppressed. Thus, the Pt-MoS2@VS catalysts are promising candidates for NOER. In addition, coupling the substitutional doping of Mo atoms to S vacancies presents great potential in improving the catalytic activity and selectivity of MoS2 for other reactions. In general, the strategy of coupling hetero-metal doping and chalcogen vacancy can be extended to enhance the catalytic activity of other TMDCs.
Collapse
Affiliation(s)
- Mamutjan Tursun
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China. .,Xinjiang Laboratory of Native Medicinal and Edible Plant Resources Chemistry, College of Chemistry and Environmental Science, Kashgar University, Kashgar, Xinjiang, 844000, China
| | - Chao Wu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710054, China.
| |
Collapse
|
27
|
Yan H, Yu T, Li H, Li Z, Tang H, Hu H, Yu H, Yin S. Synthesis of large-area monolayer and few-layer MoSe 2 continuous films by chemical vapor deposition without hydrogen assistance and formation mechanism. NANOSCALE 2021; 13:8922-8930. [PMID: 33955448 DOI: 10.1039/d1nr00552a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two dimensional (2D) MoSe2 with a layered structure has attracted extensive research due to its excellent electronic and optical properties. The controlled synthesis of large-scale and high-quality MoSe2 is highly desirable but still remains challenging. Ambient pressure chemical vapor deposition (APCVD) is an excellent method for the synthesis of 2D materials but the inevitable use of hydrogen during the growth and the easy formation of cracks in the ultrathin films still need to be solved. In the present work, we reported the synthesis of large-area continuous MoSe2 films with different layers by the APCVD method without the assistance of hydrogen on SiO2/Si substrates just by raising the reaction temperature of Se. The synthesized continuous MoSe2 films can reach several centimeters, which can be seen clearly by naked eyes, and, more importantly, the size of the monolayer film can reach up to 3 mm. The morphology, structural characteristics, and optical properties of the synthesized MoSe2 films have been investigated, demonstrating good performance and high crystallinity of the films. Raman spectra give the empirical expression of the frequency difference between E2g1 and A1g dependence of the layer number (N = 1-10 L) for CVD grown MoSe2, which is useful in layer number identification. Further, the formation mechanism of the MoSe2 continuous film is of interest as a fundamental scientific problem and needs to be studied. We proposed the wing model, boundary layer theory, and diffusion theory to account quantitatively for the formation behavior of the MoSe2 film. The presented facile growth method and theoretical model are useful to synthesize other ultrathin transition metal dichalcogenide films and understand the formation behaviors of the systems.
Collapse
Affiliation(s)
- Hui Yan
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China. and Key Laboratory of Display Materials and Photoelectric Devices, National Demonstration Center for Experimental Function Materials Education, Institute of Functional Crystal, Tianjin University of Technology, Ministry of Education, Tianjin 300384, China
| | - Tong Yu
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China. and Key Laboratory of Display Materials and Photoelectric Devices, National Demonstration Center for Experimental Function Materials Education, Institute of Functional Crystal, Tianjin University of Technology, Ministry of Education, Tianjin 300384, China
| | - Heng Li
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University, Xiamen 361005, China and Jiujiang Research Institute of Xiamen University, Jiujiang 332000, China
| | - Zhuocheng Li
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China. and Key Laboratory of Display Materials and Photoelectric Devices, National Demonstration Center for Experimental Function Materials Education, Institute of Functional Crystal, Tianjin University of Technology, Ministry of Education, Tianjin 300384, China
| | - Haitao Tang
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Hangwei Hu
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
| | - Hao Yu
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China. and Key Laboratory of Display Materials and Photoelectric Devices, National Demonstration Center for Experimental Function Materials Education, Institute of Functional Crystal, Tianjin University of Technology, Ministry of Education, Tianjin 300384, China
| | - Shougen Yin
- Tianjin Key Laboratory of Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China. and Key Laboratory of Display Materials and Photoelectric Devices, National Demonstration Center for Experimental Function Materials Education, Institute of Functional Crystal, Tianjin University of Technology, Ministry of Education, Tianjin 300384, China
| |
Collapse
|
28
|
Kang WT, Phan TL, Ahn KJ, Lee I, Kim YR, Won UY, Kim JE, Lee YH, Yu WJ. Selective Pattern Growth of Atomically Thin MoSe 2 Films via a Surface-Mediated Liquid-Phase Promoter. ACS APPLIED MATERIALS & INTERFACES 2021; 13:18056-18064. [PMID: 33827208 DOI: 10.1021/acsami.1c04005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDs) offer numerous advantages over silicon-based application in terms of atomically thin geometry, excellent opto-electrical properties, layer-number dependence, band gap variability, and lack of dangling bonds. The production of high-quality and large-scale TMD films is required with consideration of practical technology. However, the performance of scalable devices is affected by problems such as contamination and patterning arising from device processing; this is followed by an etching step, which normally damages the TMD film. Herein, we report the direct growth of MoSe2 films on selective pattern areas via a surface-mediated liquid-phase promoter using a solution-based approach. Our growth process utilizes the promoter on the selective pattern area by enhancing wettability, resulting in a highly uniform MoSe2 film. Moreover, our approach can produce other TMD films such as WSe2 films as well as control various pattern shapes, sizes, and large-scale areas, thus improving their applicability in various devices in the future. Our patterned MoSe2 field-effect transistor device exhibits a p-type dominant conduction behavior with a high on/off current ratio of ∼106. Thus, our study provides general guidance for direct selective pattern growth via a solution-based approach and the future design of integrated devices for a large-scale application.
Collapse
Affiliation(s)
- Won Tae Kang
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Thanh Luan Phan
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Kyung Jin Ahn
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Ilmin Lee
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Young Rae Kim
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Ui Yeon Won
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Ji Eun Kim
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Woo Jong Yu
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| |
Collapse
|
29
|
Gao L, Hu Z, Lu J, Liu H, Ni Z. Defect-related dynamics of photoexcited carriers in 2D transition metal dichalcogenides. Phys Chem Chem Phys 2021; 23:8222-8235. [PMID: 33875990 DOI: 10.1039/d1cp00006c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit enormous potential in the field of optoelectronics. The high performance of TMD materials and optoelectronic devices significantly depends on processes involved in photoelectric conversion, including photo-excitation, relaxation, transportation, and recombination. Remarkably, inevitable defects in materials prolong or shorten the characteristic time of these processes and even bring about new photoelectric conversion channels, namely, the defect-related relaxation pathways of photoexcited carriers tailor the performance of photoelectric applications. In recent years, there have been numerous investigations in exploring the variant transient signals caused by defects in TMDs utilizing ultrafast spectroscopies. They have the capability in providing an accurate and overall representation of ultrafast processes owing to the subtle temporal resolution. The defect-related mechanisms occurring in different time scales (from femtosecond (fs) to microsecond (μs)) play influential roles throughout the relaxation process of photoexcited species. Herein, we review the defect-related relaxation mechanisms of photoexcited species in TMDs according to the time scale utilizing ultrafast spectroscopy techniques. By interpreting and summarizing the defect-related transient signals, we furnish the direction in material design and performance optimization.
Collapse
Affiliation(s)
- Lei Gao
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
| | - Zhenliang Hu
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
| | - Junpeng Lu
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
| | - Hongwei Liu
- Jiangsu Key Lab on Opto-Electronic Technology, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
| | - Zhenhua Ni
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
| |
Collapse
|
30
|
Prucnal S, Hashemi A, Ghorbani-Asl M, Hübner R, Duan J, Wei Y, Sharma D, Zahn DRT, Ziegenrücker R, Kentsch U, Krasheninnikov AV, Helm M, Zhou S. Chlorine doping of MoSe 2 flakes by ion implantation. NANOSCALE 2021; 13:5834-5846. [PMID: 33720250 DOI: 10.1039/d0nr08935d] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The efficient integration of transition metal dichalcogenides (TMDs) into the current electronic device technology requires mastering the techniques of effective tuning of their optoelectronic properties. Specifically, controllable doping is essential. For conventional bulk semiconductors, ion implantation is the most developed method offering stable and tunable doping. In this work, we demonstrate n-type doping in MoSe2 flakes realized by low-energy ion implantation of Cl+ ions followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms with a peak temperature of about 1000 °C is enough to recrystallize implanted MoSe2. The Cl distribution in few-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An increase in the electron concentration with increasing Cl fluence is determined from the softening and red shift of the Raman-active A1g phonon mode due to the Fano effect. The electrical measurements confirm the n-type doping of Cl-implanted MoSe2. A comparison of the results of our density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities.
Collapse
Affiliation(s)
- Slawomir Prucnal
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Cogal S, Ramani S, Bhethanabotla VR, Kuhn JN. Unravelling the Origin of Enhanced Electrochemical Performance in CoSe
2
−MoSe
2
Interfaces. ChemCatChem 2021. [DOI: 10.1002/cctc.202001844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sadik Cogal
- Chemical, Biological and Materials Engineering University of South Florida Tampa FL 33620 USA
- Present address: Department of Chemistry Burdur Mehmet Akif Ersoy University Burdur, 15030 Turkey
| | - Swetha Ramani
- Department of Chemistry University of South Florida Tampa FL 33620 USA
| | - Venkat R. Bhethanabotla
- Chemical, Biological and Materials Engineering University of South Florida Tampa FL 33620 USA
- Department of Chemistry University of South Florida Tampa FL 33620 USA
| | - John N. Kuhn
- Chemical, Biological and Materials Engineering University of South Florida Tampa FL 33620 USA
- Department of Chemistry University of South Florida Tampa FL 33620 USA
| |
Collapse
|
32
|
Bertoldo F, Unocic RR, Lin YC, Sang X, Puretzky AA, Yu Y, Miakota D, Rouleau CM, Schou J, Thygesen KS, Geohegan DB, Canulescu S. Intrinsic Defects in MoS 2 Grown by Pulsed Laser Deposition: From Monolayers to Bilayers. ACS NANO 2021; 15:2858-2868. [PMID: 33576605 DOI: 10.1021/acsnano.0c08835] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pulsed laser deposition (PLD) can be considered a powerful method for the growth of two-dimensional (2D) transition-metal dichalcogenides (TMDs) into van der Waals heterostructures. However, despite significant progress, the defects in 2D TMDs grown by PLD remain largely unknown and yet to be explored. Here, we combine atomic resolution images and first-principles calculations to reveal the atomic structure of defects, grains, and grain boundaries in mono- and bilayer MoS2 grown by PLD. We find that sulfur vacancies and MoS antisites are the predominant point defects in 2D MoS2. We predict that the aforementioned point defects are thermodynamically favorable under a Mo-rich/S-poor environment. The MoS2 monolayers are polycrystalline and feature nanometer size grains connected by a high density of grain boundaries. In particular, the coalescence of nanometer grains results in the formation of 180° mirror twin boundaries consisting of distinct 4- and 8-membered rings. We show that PLD synthesis of bilayer MoS2 results in various structural symmetries, including AA' and AB, but also turbostratic with characteristic moiré patterns. Moreover, we report on the experimental demonstration of an electron beam-driven transition between the AB and AA' stacking orientations in bilayer MoS2. These results provide a detailed insight into the atomic structure of monolayer MoS2 and the role of the grain boundaries on the growth of bilayer MoS2, which has importance for future applications in optoelectronics.
Collapse
Affiliation(s)
- Fabian Bertoldo
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Raymond R Unocic
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yu-Chuan Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xiahan Sang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 Wuhan, China
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yiling Yu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Denys Miakota
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Christopher M Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jørgen Schou
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| | - Kristian S Thygesen
- CAMD and Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - David B Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stela Canulescu
- Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark
| |
Collapse
|
33
|
Liang Q, Zhang Q, Zhao X, Liu M, Wee ATS. Defect Engineering of Two-Dimensional Transition-Metal Dichalcogenides: Applications, Challenges, and Opportunities. ACS NANO 2021; 15:2165-2181. [PMID: 33449623 DOI: 10.1021/acsnano.0c09666] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Atomic defects, being the most prevalent zero-dimensional topological defects, are ubiquitous in a wide range of 2D transition-metal dichalcogenides (TMDs). They could be intrinsic, formed during the initial sample growth, or created by postprocessing. Despite the majority of TMDs being largely unaffected after losing chalcogen atoms in the outermost layer, a spectrum of properties, including optical, electrical, and chemical properties, can be significantly modulated, and potentially invoke applicable functionalities utilized in many applications. Hence, controlling chalcogen atomic defects provides an alternative avenue for engineering a wide range of physical and chemical properties of 2D TMDs. In this article, we review recent progress on the role of chalcogen atomic defects in engineering 2D TMDs, with a particular focus on device performance improvements. Various approaches for creating chalcogen atomic defects including nonstoichiometric synthesis and postgrowth treatment, together with their characterization and interpretation are systematically overviewed. The tailoring of optical, electrical, and magnetic properties, along with the device performance enhancement in electronic, optoelectronic, chemical sensing, biomedical, and catalytic activity are discussed in detail. Postformation dynamic evolution and repair of chalcogen atomic defects are also introduced. Finally, we offer our perspective on the challenges and opportunities in this field.
Collapse
Affiliation(s)
- Qijie Liang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Qian Zhang
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Meizhuang Liu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| |
Collapse
|
34
|
He T, Wang Z, Cao R, Li Q, Peng M, Xie R, Huang Y, Wang Y, Ye J, Wu P, Zhong F, Xu T, Wang H, Cui Z, Zhang Q, Gu L, Deng HX, Zhu H, Shan C, Wei Z, Hu W. Extrinsic Photoconduction Induced Short-Wavelength Infrared Photodetectors Based on Ge-Based Chalcogenides. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006765. [PMID: 33345467 DOI: 10.1002/smll.202006765] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/03/2020] [Indexed: 06/12/2023]
Abstract
2D layered photodetectors have been widely researched for intriguing optoelectronic properties but their application fields are limited by the bandgap. Extending the detection waveband can significantly enrich functionalities and applications of photodetectors. For example, after breaking through bandgap limitation, extrinsic Si photodetectors are used for short-wavelength infrared or even long-wavelength infrared detection. Utilizing extrinsic photoconduction to extend the detection waveband of 2D layered photodetectors is attractive and desirable. However, extrinsic photoconduction has yet not been observed in 2D layered materials. Here, extrinsic photoconduction-induced short-wavelength infrared photodetectors based on Ge-based chalcogenides are reported for the first time and the effectiveness of intrinsic point defects are demonstrated. The detection waveband of room-temperature extrinsic GeSe photodetectors with the assistance of Ge vacancies is broadened to 1.6 µm. Extrinsic GeSe photodetectors have an excellent external quantum efficiency (0.5%) at the communication band of 1.31 µm and polarization-resolved capability to subwaveband radiation. Moreover, room-temperature extrinsic GeS photodetectors with a detection waveband to the communication band of 1.55 µm further verify the versatility of intrinsic point defects. This approach provides design strategies to enrich the functionalities of 2D layered photodetectors.
Collapse
Affiliation(s)
- Ting He
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhen Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ruyue Cao
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
| | - Qing Li
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Meng Peng
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
| | - Runzhang Xie
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan Huang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
| | - Yang Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Jiafu Ye
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peisong Wu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fang Zhong
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
| | - Tengfei Xu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
| | - Hailu Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhuangzhuang Cui
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hui-Xiong Deng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
| | - He Zhu
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Chongxin Shan
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China
| | - Zhongming Wei
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
| | - Weida Hu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yutian Road, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| |
Collapse
|
35
|
Sukhanova EV, Kvashnin DG, Popov ZI. Induced spin polarization in graphene via interactions with halogen doped MoS 2 and MoSe 2 monolayers by DFT calculations. NANOSCALE 2020; 12:23248-23258. [PMID: 33206100 DOI: 10.1039/d0nr06287a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Magnetic halogen doped MoX2 (X = S and Se) monolayers influenced the electronic structure of graphene through a proximity effect. This process was observed using state-of-the-art calculations. It was found that the substitution of a single chalcogen atom with a halogen atom (F, Cl, Br, and I) results in n-type doping of MoX2. An additional electron from the dopant is localized on binding orbitals with the nearest Mo atoms and leads to the formation of magnetism in the dichalcogenide layer. Detailed analysis of halogen doped MoX2/graphene heterostructures demonstrated the induction of spin polarization in graphene near the Fermi energy. Significant spin polarization near the Fermi energy and n-type doping were observed in the graphene layer of MoSe2/graphene heterostructures with MoSe2 doped with iodine. At the same time, fluorine-doped MoSe2 does not cause n-doping in graphene, while spin polarization still takes place. The possibility for the detection of the arrangement of the halogen impurities at the MoX2 basal plane even with the graphene layer deposited on top was demonstrated through STM measurements which will be undoubtedly useful for the fabrication of electronic schemes and elements based on the proposed heterostructures for their further application in nanoelectronics and spintronics.
Collapse
Affiliation(s)
- Ekaterina V Sukhanova
- Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region, 141701, Russian Federation.
| | | | | |
Collapse
|
36
|
Zhang X, Wang S, Lee CK, Cheng CM, Lan JC, Li X, Qiao J, Tao X. Unravelling the effect of sulfur vacancies on the electronic structure of the MoS 2 crystal. Phys Chem Chem Phys 2020; 22:21776-21783. [PMID: 32966363 DOI: 10.1039/c9cp07004d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molybdenum disulfide (MoS2) is one of the two-dimensional layered semiconductor transition metal dichalcogenides (TMDCs) with great potential in electronics, optoelectronics, and spintronic devices. Sulfur vacancies in MoS2 are the most prevalent defects. However, the effect of sulfur vacancies on the electronic structure of MoS2 is still in dispute. Here we experimentally and theoretically investigated the effect of sulfur vacancies in MoS2. The vacancies were intentionally introduced by thermal annealing of MoS2 crystals in a vacuum environment. Angle-resolved photoemission spectroscopy (ARPES) was used directly to observe the electronic structure of the MoS2 single crystals. The experimental result distinctly revealed the appearance of an occupied defect state just above the valence band maximum (VBM) and an upward shift of the VBM after creating sulfur vacancies. In addition, density functional theory (DFT) calculations also confirmed the existence of the occupied defect state close to the VBM as well as two deep unoccupied states induced by the sulfur vacancies. Our results provide evidence to contradict that sulfur vacancies indicate the origin of n-type behaviour in MoS2. This work provides a rational strategy for tuning the electronic structures of MoS2.
Collapse
Affiliation(s)
- Xixia Zhang
- State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Taghinejad H, Taghinejad M, Eftekhar AA, Li Z, West MP, Javani MH, Abdollahramezani S, Zhang X, Tian M, Johnson-Averette T, Ajayan PM, Vogel EM, Shi SF, Cai W, Adibi A. Synthetic Engineering of Morphology and Electronic Band Gap in Lateral Heterostructures of Monolayer Transition Metal Dichalcogenides. ACS NANO 2020; 14:6323-6330. [PMID: 32364693 DOI: 10.1021/acsnano.0c02885] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Heterostructures of two-dimensional transition metal dichalcogenides (TMDs) can offer a plethora of opportunities in condensed matter physics, materials science, and device engineering. However, despite state-of-the-art demonstrations, most current methods lack enough degrees of freedom for the synthesis of heterostructures with engineerable properties. Here, we demonstrate that combining a postgrowth chalcogen-swapping procedure with the standard lithography enables the realization of lateral TMD heterostructures with controllable dimensions and spatial profiles in predefined locations on a substrate. Indeed, our protocol receives a monolithic TMD monolayer (e.g., MoSe2) as the input and delivers lateral heterostructures (e.g., MoSe2-MoS2) with fully engineerable morphologies. In addition, through establishing MoS2xSe2(1-x)-MoS2ySe2(1-y) lateral junctions, our synthesis protocol offers an extra degree of freedom for engineering the band gap energies up to ∼320 meV on each side of the heterostructure junction via changing x and y independently. Our electron microscopy analysis reveals that such continuous tuning stems from the random intermixing of sulfur and selenium atoms following the chalcogen swapping. We believe that, by adding an engineering flavor to the synthesis of TMD heterostructures, our study lowers the barrier for the integration of two-dimensional materials into practical optoelectronic platforms.
Collapse
Affiliation(s)
- Hossein Taghinejad
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Mohammad Taghinejad
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Ali A Eftekhar
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zhipeng Li
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Matthew P West
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Mohammad H Javani
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Department of Physics, Kennesaw State University, Marietta, Georgia 30060, United States
| | - Sajjad Abdollahramezani
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Xiang Zhang
- School of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005, United States
| | - Mengkun Tian
- Institute of Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Thomas Johnson-Averette
- Institute of Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Pulickel M Ajayan
- School of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005, United States
| | - Eric M Vogel
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Su-Fei Shi
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Wenshan Cai
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Ali Adibi
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| |
Collapse
|
38
|
Nguyen GD, Oyedele AD, Haglund A, Ko W, Liang L, Puretzky AA, Mandrus D, Xiao K, Li AP. Atomically Precise PdSe 2 Pentagonal Nanoribbons. ACS NANO 2020; 14:1951-1957. [PMID: 32023412 DOI: 10.1021/acsnano.9b08390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We report atomically precise pentagonal PdSe2 nanoribbons (PNRs) fabricated on a pristine PdSe2 substrate with a hybrid method of top-down and bottom-up processes. The PNRs form a uniform array of dimer structure with a width of 2.4 nm and length of more than 200 nm. In situ four-probe scanning tunneling microscopy (STM) reveals metallic behavior of PNRs with ballistic transport for at least 20 nm in length. Density functional theory calculations produce a semiconducting density of states of isolated PNRs and find that the band gap narrows and disappears quickly once considering coupling between PNR stacking layers or interaction with the PdSe2 substrate. The coupling of PNRs is further corroborated by Raman spectroscopy and field-effect transistor measurements. The facile method of fabricating atomically precise PNRs offers an air-stable functional material for dimensional control.
Collapse
Affiliation(s)
- Giang D Nguyen
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Stewart Blusson Quantum Matter Institute , University of British Columbia , Vancouver , British Columbia V6T 1Z4 , Canada
| | - Akinola D Oyedele
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Amanda Haglund
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee , Knoxville , Tennessee 37996 , United States
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Wonhee Ko
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Liangbo Liang
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - David Mandrus
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Kai Xiao
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - An-Ping Li
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| |
Collapse
|
39
|
Wang X, Zhang Y, Si H, Zhang Q, Wu J, Gao L, Wei X, Sun Y, Liao Q, Zhang Z, Ammarah K, Gu L, Kang Z, Zhang Y. Single-Atom Vacancy Defect to Trigger High-Efficiency Hydrogen Evolution of MoS 2. J Am Chem Soc 2020; 142:4298-4308. [PMID: 31999446 DOI: 10.1021/jacs.9b12113] [Citation(s) in RCA: 256] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Defect engineering is widely applied in transition metal dichalcogenides (TMDs) to achieve electrical, optical, magnetic, and catalytic regulation. Vacancies, regarded as a type of extremely delicate defect, are acknowledged to be effective and flexible in general catalytic modulation. However, the influence of vacancy states in addition to concentration on catalysis still remains vague. Thus, via high throughput calculations, the optimized sulfur vacancy (S-vacancy) state in terms of both concentration and distribution is initially figured out among a series of MoS2 models for the hydrogen evolution reaction (HER). In order to realize it, a facile and mild H2O2 chemical etching strategy is implemented to introduce homogeneously distributed single S-vacancies onto the MoS2 nanosheet surface. By systematic tuning of the etching duration, etching temperature, and etching solution concentration, comprehensive modulation of the S-vacancy state is achieved. The optimal HER performance reaches a Tafel slope of 48 mV dec-1 and an overpotential of 131 mV at a current density of 10 mA cm-2, indicating the superiority of single S-vacancies over agglomerate S-vacancies. This is ascribed to the more effective surface electronic structure engineering as well as the boosted electrical transport properties. By bridging the gap, to some extent, between precise design from theory and practical modulation in experiments, the proposed strategy extends defect engineering to a more sophisticated level to further unlock the potential of catalytic performance enhancement.
Collapse
Affiliation(s)
- Xin Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yuwei Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Haonan Si
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Wu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Li Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Xiaofu Wei
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yu Sun
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qingliang Liao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zheng Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Kausar Ammarah
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Zhuo Kang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yue Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, China.,State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| |
Collapse
|
40
|
Gao L, Liao Q, Zhang X, Liu X, Gu L, Liu B, Du J, Ou Y, Xiao J, Kang Z, Zhang Z, Zhang Y. Defect-Engineered Atomically Thin MoS 2 Homogeneous Electronics for Logic Inverters. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906646. [PMID: 31743525 DOI: 10.1002/adma.201906646] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Ultrathin molybdenum disulfide (MoS2 ) presents ideal properties for building next-generation atomically thin circuitry. However, it is difficult to construct logic units of MoS2 monolayer using traditional silicon-based doping schemes, such as atomic substitution and ion implantation, as they cause lattice disruption and doping instability. An accurate and feasible electronic structure modulation strategy from defect engineering is proposed to construct homogeneous electronics for MoS2 monolayer logic inverters. By utilizing the energy-matched electron induction of the solution process, numerous pure and lattice-stable monosulfur vacancies (Vmonos ) are introduced to modulate the electronic structure of monolayer MoS2 via a shallow trapping effect. The resulting modulation effectively reduces the electronic concentration of MoS2 and improves the work function by 100 meV. Under modulation of Vmonos , an atomically thin homogenous monolayer MoS2 logic inverter with a voltage gain of 4 is successfully constructed. A brand-new and practical design route of defect modulation for 2D-based circuit development is provided.
Collapse
Affiliation(s)
- Li Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Qingliang Liao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiankun Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiaozhi Liu
- Collaborative Innovation Center of Quantum Matter, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lin Gu
- Collaborative Innovation Center of Quantum Matter, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Baishan Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Junli Du
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yang Ou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Jiankun Xiao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhuo Kang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zheng Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yue Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| |
Collapse
|
41
|
Qin Z, Loh L, Wang J, Xu X, Zhang Q, Haas B, Alvarez C, Okuno H, Yong JZ, Schultz T, Koch N, Dan J, Pennycook SJ, Zeng D, Bosman M, Eda G. Growth of Nb-Doped Monolayer WS 2 by Liquid-Phase Precursor Mixing. ACS NANO 2019; 13:10768-10775. [PMID: 31491079 DOI: 10.1021/acsnano.9b05574] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Controlled substitutional doping of two-dimensional transition-metal dichalcogenides (TMDs) is of fundamental importance for their applications in electronics and optoelectronics. However, achieving p-type conductivity in MoS2 and WS2 is challenging because of their natural tendency to form n-type vacancy defects. Here, we report versatile growth of p-type monolayer WS2 by liquid-phase mixing of a host tungsten source and niobium dopant. We show that crystallites of WS2 with different concentrations of substitutionally doped Nb up to 1014 cm-2 can be grown by reacting solution-deposited precursor film with sulfur vapor at 850 °C, reflecting the good miscibility of the precursors in the liquid phase. Atomic-resolution characterization with aberration-corrected scanning transmission electron microscopy reveals that the Nb concentration along the outer edge region of the flakes increases consistently with the molar concentration of Nb in the precursor solution. We further demonstrate that ambipolar field-effect transistors can be fabricated based on Nb-doped monolayer WS2.
Collapse
Affiliation(s)
- Ziyu Qin
- State Key Laboratory of Materials Processing and Die Mould Technology , Huazhong University of Science and Technology (HUST) , No. 1037, Luoyu Road , Wuhan 430074 , China
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
| | - Leyi Loh
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
- Department of Materials Science and Engineering , National University of Singapore , 9 Engineering Drive 1 , Singapore 117575 , Singapore
| | - Junyong Wang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
| | - Xiaomin Xu
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstrasse 15 , 12489 Berlin , Germany
| | - Qi Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
| | - Benedikt Haas
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstrasse 15 , 12489 Berlin , Germany
| | - Carlos Alvarez
- Univ. Grenoble Alpes , CEA, INAC-MEM , F-38000 Grenoble , France
| | - Hanako Okuno
- Univ. Grenoble Alpes , CEA, INAC-MEM , F-38000 Grenoble , France
| | - Justin Zhou Yong
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
| | - Thorsten Schultz
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstrasse 15 , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Str. 15 , 12489 Berlin , Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstrasse 15 , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Str. 15 , 12489 Berlin , Germany
| | - Jiadong Dan
- Department of Materials Science and Engineering , National University of Singapore , 9 Engineering Drive 1 , Singapore 117575 , Singapore
| | - Stephen J Pennycook
- Department of Materials Science and Engineering , National University of Singapore , 9 Engineering Drive 1 , Singapore 117575 , Singapore
| | - Dawen Zeng
- State Key Laboratory of Materials Processing and Die Mould Technology , Huazhong University of Science and Technology (HUST) , No. 1037, Luoyu Road , Wuhan 430074 , China
| | - Michel Bosman
- Department of Materials Science and Engineering , National University of Singapore , 9 Engineering Drive 1 , Singapore 117575 , Singapore
| | - Goki Eda
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543 , Singapore
- Centre for Advanced 2D Materials , National University of Singapore , 2 Science Drive 2 , Singapore 117542 , Singapore
| |
Collapse
|
42
|
Barja S, Refaely-Abramson S, Schuler B, Qiu DY, Pulkin A, Wickenburg S, Ryu H, Ugeda MM, Kastl C, Chen C, Hwang C, Schwartzberg A, Aloni S, Mo SK, Frank Ogletree D, Crommie MF, Yazyev OV, Louie SG, Neaton JB, Weber-Bargioni A. Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides. Nat Commun 2019; 10:3382. [PMID: 31358753 PMCID: PMC6662818 DOI: 10.1038/s41467-019-11342-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 07/05/2019] [Indexed: 12/24/2022] Open
Abstract
Chalcogen vacancies are generally considered to be the most common point defects in transition metal dichalcogenide (TMD) semiconductors because of their low formation energy in vacuum and their frequent observation in transmission electron microscopy studies. Consequently, unexpected optical, transport, and catalytic properties in 2D-TMDs have been attributed to in-gap states associated with chalcogen vacancies, even in the absence of direct experimental evidence. Here, we combine low-temperature non-contact atomic force microscopy, scanning tunneling microscopy and spectroscopy, and state-of-the-art ab initio density functional theory and GW calculations to determine both the atomic structure and electronic properties of an abundant chalcogen-site point defect common to MoSe2 and WS2 monolayers grown by molecular beam epitaxy and chemical vapor deposition, respectively. Surprisingly, we observe no in-gap states. Our results strongly suggest that the common chalcogen defects in the described 2D-TMD semiconductors, measured in vacuum environment after gentle annealing, are oxygen substitutional defects, rather than vacancies.
Collapse
Affiliation(s)
- Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain.
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Artem Pulkin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Sebastian Wickenburg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Miguel M Ugeda
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christopher Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan, 46241, Korea
| | - Adam Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA.
| | | |
Collapse
|
43
|
Huang B, Tian F, Shen Y, Zheng M, Zhao Y, Wu J, Liu Y, Pennycook SJ, Thong JTL. Selective Engineering of Chalcogen Defects in MoS 2 by Low-Energy Helium Plasma. ACS APPLIED MATERIALS & INTERFACES 2019; 11:24404-24411. [PMID: 31199625 DOI: 10.1021/acsami.9b05507] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Structural defects in two-dimensional transition-metal dichalcogenides can significantly modify the material properties. Previous studies have shown that chalcogen defects can be created by physical sputtering, but the energetic ions can potentially displace transition-metal atoms at the same time, leading to ambiguous results and in some cases, degradation of material quality. In this work, selective sputtering of S atoms in monolayer MoS2 without damaging the Mo sublattice is demonstrated with low-energy helium plasma treatment. Based on X-ray photoelectron spectroscopy analysis, wide-range tuning of S defect concentration is achieved by controlling the ion energy and sputtering time. Furthermore, characterization with scanning transmission electron microscopy confirms that by keeping the ion energy low, the Mo sublattice remains intact. The properties of MoS2 at different defect concentrations are also characterized. In situ device measurement shows that the flake can be tuned from a semiconducting to metallic-like behavior by introducing S defects due to the creation of mid-gap states. When the defective MoS2 is exposed to air, the S defects are soon passivated, with oxygen atoms filling the defect sites.
Collapse
Affiliation(s)
- Binjie Huang
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
- NUS Graduate School for Integrative Sciences and Engineering , National University of Singapore , 119077 , Singapore
| | - Feng Tian
- Center for Advanced 2D Materials , National University of Singapore , 117542 , Singapore
| | - Youde Shen
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
| | - Minrui Zheng
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
| | - Yunshan Zhao
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
| | - Jing Wu
- Institute of Materials Research and Engineering , Agency for Science Technology and Research , 138634 , Singapore
| | - Yi Liu
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
| | - Stephen J Pennycook
- Center for Advanced 2D Materials , National University of Singapore , 117542 , Singapore
- Department of Materials Science and Engineering , National University of Singapore , 117575 , Singapore
| | - John T L Thong
- Department of Electrical and Computer Engineering , National University of Singapore , 117583 , Singapore
| |
Collapse
|
44
|
Oyedele AD, Yang S, Feng T, Haglund AV, Gu Y, Puretzky AA, Briggs D, Rouleau CM, Chisholm MF, Unocic RR, Mandrus D, Meyer HM, Pantelides ST, Geohegan DB, Xiao K. Defect-Mediated Phase Transformation in Anisotropic Two-Dimensional PdSe 2 Crystals for Seamless Electrical Contacts. J Am Chem Soc 2019; 141:8928-8936. [PMID: 31090414 DOI: 10.1021/jacs.9b02593] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The failure to achieve stable Ohmic contacts in two-dimensional material devices currently limits their promised performance and integration. Here we demonstrate that a phase transformation in a region of a layered semiconductor, PdSe2, can form a contiguous metallic Pd17Se15 phase, leading to the formation of seamless Ohmic contacts for field-effect transistors. This phase transition is driven by defects created by exposure to an argon plasma. Cross-sectional scanning transmission electron microscopy is combined with theoretical calculations to elucidate how plasma-induced Se vacancies mediate the phase transformation. The resulting Pd17Se15 phase is stable and shares the same native chemical bonds with the original PdSe2 phase, thereby forming an atomically sharp Pd17Se15/PdSe2 interface. These Pd17Se15 contacts exhibit a low contact resistance of ∼0.75 kΩ μm and Schottky barrier height of ∼3.3 meV, enabling nearly a 20-fold increase of carrier mobility in PdSe2 transistors compared to that of traditional Ti/Au contacts. This finding opens new possibilities in the development of better electrical contacts for practical applications of 2D materials.
Collapse
Affiliation(s)
| | | | - Tianli Feng
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | | | - Yiyi Gu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials , Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | | | | | | | | | | | | | | | - Sokrates T Pantelides
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | | | | |
Collapse
|
45
|
Liu J, Zhou L, Huang K, Song X, Chen Y, Liang X, Gao J, Xiao X, Rümmeli MH, Fu L. Regulation of Two-Dimensional Lattice Deformation Recovery. iScience 2019; 13:277-283. [PMID: 30875609 PMCID: PMC6416774 DOI: 10.1016/j.isci.2019.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/23/2019] [Accepted: 02/25/2019] [Indexed: 11/26/2022] Open
Abstract
The lattice directly determines the electronic structure, and it enables controllably tailoring the properties by deforming the lattices of two-dimensional (2D) materials. Owing to the unbalanced electrostatic equilibrium among the dislocated atoms, the deformed lattice is thermodynamically unstable and would recover to the initial state. Here, we demonstrate that the recovery of deformed 2D lattices could be directly regulated via doping metal donors to reconstruct electrostatic equilibrium. Compared with the methods that employed external force fields with intrinsic instability and nonuniformity, the stretched 2D molybdenum diselenide (MoSe2) could be uniformly retained and permanently preserved via doping metal atoms with more outermost electrons and smaller electronegativity than Mo. We believe that the proposed strategy could open up a new avenue in directly regulating the atomic-thickness lattice and promote its practical applications based on 2D crystals. Regulation of the deformation recovery of 2D lattices by doping metal donors Achieving 2D MoSe2 with uniformly and permanently stabilized lattice deformation Demonstration of the efficient micromanipulation of strict 2D lattices
Collapse
Affiliation(s)
- Jinxin Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Lu Zhou
- Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Ke Huang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Xianyin Song
- Department of Physics and Key Laboratory of Artificial Micro and Nanostructures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and Center for Ion Beam Application, Wuhan University, Wuhan 430072, China
| | - Yunxu Chen
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaoyang Liang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Jin Gao
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou, Nano Science and Technology, Soochow University, Suzhou 215006, China
| | - Xiangheng Xiao
- Department of Physics and Key Laboratory of Artificial Micro and Nanostructures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and Center for Ion Beam Application, Wuhan University, Wuhan 430072, China
| | - Mark H Rümmeli
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou, Nano Science and Technology, Soochow University, Suzhou 215006, China; Leibniz Institute for Solid State and Materials Research Dresden, P.O. Box 270116, Dresden 01069, Germany; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, Zabrze 41-819, Poland
| | - Lei Fu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China; Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.
| |
Collapse
|
46
|
Hassan MS, Bera S, Gupta D, Ray SK, Sapra S. MoSe 2-Cu 2S Vertical p-n Nanoheterostructures for High-Performance Photodetectors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:4074-4083. [PMID: 30624044 DOI: 10.1021/acsami.8b16205] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Heterostructures based on atomically thin two-dimensional layered transition metal dichalcogenides are highly promising for optoelectronic device applications owing to their tunable optical and electronic properties. However, the synthesis of heterostructures with desired materials having proper interfacial contacts has been a challenging task. Here, we develop a colloidal synthetic route for the design of MoSe2-Cu2S nanoheterostructures, where the Cu2S islands grow vertically on top of the defect sites present on the MoSe2 surface, thereby forming a vertical p-n junction having plasmonic characteristics. These MoSe2-Cu2S nanoheterostructures are used to fabricate photodetectors with superior photoresponse characteristics. The fabricated device exhibits a broad-band spectral photoresponse over the visible to near-infrared range with a peak responsivity of 410 mA W-1 at -2.0 V and over 3000-fold photo-to-dark current ratio. The superior device performance of MoSe2-Cu2S over only MoSe2 devices is due to the combined effect of the formation of the p-n junction, pronounced light-matter interactions, and passivation of surface defects. This study would pave the way for designing a new class of nanoheterostructured materials for their potential applications in next-generation photonic devices.
Collapse
Affiliation(s)
- Md Samim Hassan
- Department of Chemistry , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016 , India
| | - Susnata Bera
- Department of Chemistry , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016 , India
| | - Divya Gupta
- Department of Chemistry , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016 , India
| | - Samit K Ray
- Department of Physics , Indian Institute of Technology Kharagpur , Kharagpur 721302 , West Bengal , India
- S. N. Bose National Centre for Basic Sciences , Kolkata 700106 , West Bengal , India
| | - Sameer Sapra
- Department of Chemistry , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016 , India
| |
Collapse
|
47
|
Taghinejad H, Rehn DA, Muccianti C, Eftekhar AA, Tian M, Fan T, Zhang X, Meng Y, Chen Y, Nguyen TV, Shi SF, Ajayan PM, Schaibley J, Reed EJ, Adibi A. Defect-Mediated Alloying of Monolayer Transition-Metal Dichalcogenides. ACS NANO 2018; 12:12795-12804. [PMID: 30433762 DOI: 10.1021/acsnano.8b07920] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Alloying plays a central role in tailoring the material properties of 2D transition-metal dichalcogenides (TMDs). However, despite widespread reports, the details of the alloying mechanism in 2D TMDs have remained largely unknown and are yet to be further explored. Here, we combine a set of systematic experiments with ab initio density functional theory (DFT) calculations to unravel a defect-mediated mechanism for the alloying of monolayer TMD crystals. In our alloying approach, a monolayer MoSe2 film serves as a host crystal in which exchanging selenium (Se) atoms with sulfur (S) atoms yields a MoS2 xSe2(1- x) alloy. Our study reveals that the driving force required for the alloying of CVD-grown films with abundant vacancy-type defects is significantly lower than that required for the alloying of exfoliated films with fewer vacancies. Indeed, we show that pre-existing Se vacancies in the host MoSe2 lattice mediate the replacement of chalcogen atoms and facilitate the synthesis of MoS2 xSe2(1- x) alloys. Our DFT calculations suggest that S atoms can bind to Se vacancies and then diffuse throughout the host MoSe2 lattice via exchanging the position with Se vacancies, further supporting our proposed defect-mediated alloying mechanism. Beside native vacancy defects, we show that the existence of large-scale defects in CVD-grown MoSe2 films causes the fracture of alloys under the alloying-induced strain, while no such effect is observed in exfoliated MoSe2 films. Our study provides a deep insight into the details of the alloying mechanism and enables the synthesis of 2D alloys with tunable properties.
Collapse
Affiliation(s)
| | | | - Christine Muccianti
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | | | | | | | - Xiang Zhang
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | | | | | | | | | - Pulickel M Ajayan
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - John Schaibley
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | | | | |
Collapse
|
48
|
Wu H, Zhao X, Song D, Tian F, Wang J, Loh KP, Pennycook SJ. Progress and prospects of aberration-corrected STEM for functional materials. Ultramicroscopy 2018; 194:182-192. [DOI: 10.1016/j.ultramic.2018.08.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/14/2018] [Accepted: 08/07/2018] [Indexed: 11/16/2022]
|
49
|
Biacchi AJ, Le ST, Alberding BG, Hagmann JA, Pookpanratana SJ, Heilweil EJ, Richter CA, Hight Walker AR. Contact and Noncontact Measurement of Electronic Transport in Individual 2D SnS Colloidal Semiconductor Nanocrystals. ACS NANO 2018; 12:10045-10060. [PMID: 30247875 PMCID: PMC6348888 DOI: 10.1021/acsnano.8b04620] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Colloidal-based solution syntheses offer a scalable and cost-efficient means of producing 2D nanomaterials in high yield. While much progress has been made toward the controlled and tailorable synthesis of semiconductor nanocrystals in solution, it remains a substantial challenge to fully characterize the products' inherent electronic transport properties. This is often due to their irregular morphology or small dimensions, which demand the formation of colloidal assemblies or films as a prerequisite to performing electrical measurements. Here, we report the synthesis of nearly monodisperse 2D colloidal nanocrystals of semiconductor SnS and a thorough investigation of the intrinsic electronic transport properties of single crystals. We utilize a combination of multipoint contact probe measurements and ultrafast terahertz spectroscopy to determine the carrier concentration, carrier mobility, conductivity/resistivity, and majority carrier type of individual colloidal semiconductor nanocrystals. Employing this metrological approach, we compare the electronic properties extracted for distinct morphologies of 2D SnS and relate them to literature values. Our results indicate that the electronic transport of colloidal semiconductors may be tuned through prudent selection of the synthetic conditions. We find that these properties compare favorably to SnS grown using vapor deposition techniques, illustrating that colloidal solution synthesis is a promising route to scalable production of nanoscale 2D materials.
Collapse
Affiliation(s)
- Adam J. Biacchi
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Son T. Le
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Brian G. Alberding
- Remote Sensing Group, Sensor Science Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, 20899, United States
| | - Joseph A. Hagmann
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Sujitra J. Pookpanratana
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Edwin J. Heilweil
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Curt A. Richter
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Angela R. Hight Walker
- Nanoelectronics Group, Engineering Physics Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| |
Collapse
|
50
|
Refaely-Abramson S, Qiu DY, Louie SG, Neaton JB. Defect-Induced Modification of Low-Lying Excitons and Valley Selectivity in Monolayer Transition Metal Dichalcogenides. PHYSICAL REVIEW LETTERS 2018; 121:167402. [PMID: 30387666 DOI: 10.1103/physrevlett.121.167402] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Indexed: 05/24/2023]
Abstract
We study the effect of point-defect chalcogen vacancies on the optical properties of monolayer transition metal dichalcogenides using ab initio GW and Bethe-Salpeter equation calculations. We find that chalcogen vacancies introduce unoccupied in-gap states and occupied resonant defect states within the quasiparticle continuum of the valence band. These defect states give rise to a number of strongly bound defect excitons and hybridize with excitons of the pristine system, reducing the valley-selective circular dichroism. Our results suggest a pathway to tune spin-valley polarization and other optical properties through defect engineering.
Collapse
Affiliation(s)
- Sivan Refaely-Abramson
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720, USA
| |
Collapse
|