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Tang Y, Wang Y, Cheng X, Zhang H. Strain and Electric Field Engineering of G-ZnO/SnXY (X, Y = S, Se) S-Scheme Heterostructures for Photocatalyst and Electronic Device Applications: A Hybrid DFT Calculation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:27381-27393. [PMID: 38752270 DOI: 10.1021/acsami.4c03666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Using hybrid density functional theory calculations, we systematically study the biaxial strain and electric field modulated electronic properties of g-ZnO/SnS2, g-ZnO/SnSe2, and g-ZnO/SnSSe S-scheme van der Waals heterostructures (vdWHs). g-ZnO/SnS2 and g-ZnO/SnSSe are found to be promising photocatalysts for water splitting with high solar-to-hydrogen efficiencies, even under acidic, alkaline, and high-stress conditions. The strain effect on the bandgaps of g-ZnO/SnXY is explained in detail according to the correlation between geometry structure and orbital hybridization of SnXY, which could help understand the strain-induced band structure evolutions in other SnXY (X, Y = S, Se)-based vdWHs. It is surprising that under an external electric field, g-ZnO/SnS2, g-ZnO/SnSe2, and g-ZnO/SnSSe can offer the occupied nearly free-electron (NFE) states. In many materials, NFE states are usually unoccupied and is not conducive to the charge transport. The NFE state in g-ZnO/SnSe2 is the most sensitive to the electric field and might be promising electron transport channel in nanoelectronic devices. g-ZnO/SnSe2 might also have application potential in gas sensors and high-temperature superconductors.
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Affiliation(s)
- Yue Tang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - YiPeng Wang
- College of Applied Technology, Shenzhen University, Shenzhen 518061, China
| | - Xinlu Cheng
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Hong Zhang
- College of Physics, Sichuan University, Chengdu 610064, China
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2
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Wang H, Xia H, Liu Y, Chen Y, Xie R, Wang Z, Wang P, Miao J, Wang F, Li T, Fu L, Martyniuk P, Xu J, Hu W, Lu W. Room-temperature low-threshold avalanche effect in stepwise van-der-Waals homojunction photodiodes. Nat Commun 2024; 15:3639. [PMID: 38684745 PMCID: PMC11059283 DOI: 10.1038/s41467-024-47958-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 04/16/2024] [Indexed: 05/02/2024] Open
Abstract
Avalanche or carrier-multiplication effect, based on impact ionization processes in semiconductors, has a great potential for enhancing the performance of photodetector and solar cells. However, in practical applications, it suffers from high threshold energy, reducing the advantages of carrier multiplication. Here, we report on a low-threshold avalanche effect in a stepwise WSe2 structure, in which the combination of weak electron-phonon scattering and high electric fields leads to a low-loss carrier acceleration and multiplication. Owing to this effect, the room-temperature threshold energy approaches the fundamental limit, Ethre ≈ Eg, where Eg is the bandgap of the semiconductor. Our findings offer an alternative perspective on the design and fabrication of future avalanche and hot-carrier photovoltaic devices.
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Affiliation(s)
- Hailu Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Xia
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Yaqian Liu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
| | - Yue Chen
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Runzhang Xie
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- 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, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peng Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jinshui Miao
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fang Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tianxin Li
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lan Fu
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT, 2601, Australia
| | - Piotr Martyniuk
- Institute of Applied Physics, Military University of Technology, 2 Kaliskiego St., 00-908, Warsaw, Poland
| | - Jianbin Xu
- Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Weida Hu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Wei Lu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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3
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Xu L, Xu L, Lan J, Li Y, Li Q, Wang A, Guo Y, Ang YS, Quhe R, Lu J. Sub-5 nm Ultrathin In 2O 3 Transistors for High-Performance and Low-Power Electronic Applications. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38676632 DOI: 10.1021/acsami.4c01353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2024]
Abstract
Ultrathin oxide semiconductors are promising candidates for back-end-of-line (BEOL) compatible transistors and monolithic three-dimensional integration. Experimentally, ultrathin indium oxide (In2O3) field-effect transistors (FETs) with thicknesses down to 0.4 nm exhibit an extremely high drain current (104 μA/μm) and transconductance (4000 μS/μm). Here, we employ ab initio quantum transport simulation to investigate the performance limit of sub-5 nm gate length (Lg) ultrathin In2O3 FETs. Based on the International Technology Roadmap for Semiconductors (ITRS) criteria for high-performance (HP) devices, the scaling limit of ultrathin In2O3 FETs can reach 2 nm in terms of on-state current, delay time, and power dissipation. The wide bandgap nature of ultrathin In2O3 (3.0 eV) renders it a suitable candidate for ITRS low-power (LP) electronics with Lg down to 3 nm. Notably, both the HP and LP ultrathin In2O3 FETs exhibit superior energy-delay products as compared to those of other common 2D semiconductors such as monolayer MoS2 and MoTe2. These findings unveil the potential of ultrathin In2O3 in HP and LP nanoelectronic device applications.
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Affiliation(s)
- Linqiang Xu
- State Key Laboratory of Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China
- Science, Mathematics and Technology, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore
| | - Lianqiang Xu
- School of Physics and Electronic Information Engineering, Engineering Research Center of Nanostructure and Functional Materials, Ningxia Normal University, Guyuan 756000, China
| | - Jun Lan
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yida Li
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qiuhui Li
- State Key Laboratory of Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China
| | - Aili Wang
- College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
- Zhejiang University─University of Illinois at Urbana─Champaign Institute, Zhejiang University, Haining 314400, China
| | - Ying Guo
- School of Physics and Telecommunication Engineering, Shaanxi Key Laboratory of Catalysis, Shaanxi University of Technology, Hanzhong 723001, People's Republic of China
| | - Yee Sin Ang
- Science, Mathematics and Technology, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore
| | - Ruge Quhe
- State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Jing Lu
- State Key Laboratory of Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing 100871, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226000, China
- Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing 100871, China
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Maccagnani P, Pieruccini M. Impact of Surface States in Graphene/ p-Si Schottky Diodes. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1997. [PMID: 38730804 PMCID: PMC11084165 DOI: 10.3390/ma17091997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 04/19/2024] [Accepted: 04/21/2024] [Indexed: 05/13/2024]
Abstract
Graphene-silicon Schottky diodes are intriguing devices that straddle the border between classical models and two-dimensional ones. Many papers have been published in recent years studying their operation based on the classical model developed for metal-silicon Schottky diodes. However, the results obtained for diode parameters vary widely in some cases showing very large deviations with respect to the expected range. This indicates that our understanding of their operation remains incomplete. When modeling these devices, certain aspects strictly connected with the quantum mechanical features of both graphene and the interface with silicon play a crucial role and must be considered. In particular, the dependence of the graphene Fermi level on carrier density, the relation of the latter with the density of surface states in silicon and the coupling between in-plane and out-of-plane dynamics in graphene are key aspects for the interpretation of their behavior. Within the thermionic regime, we estimate the zero-bias Schottky barrier height and the density of silicon surface states in graphene/type-p silicon diodes by adapting a kown model and extracting ideality index values close to unity. The ohmic regime, beyond the flat band potential, is modeled with an empirical law, and the current density appears to be roughly proportional to the electric field at the silicon interface; moreover, the graphene-to-silicon electron tunneling efficiency drops significantly in the transition from the thermionic to ohmic regime. We attribute these facts to (donor) silicon surface states, which tend to be empty in the ohmic regime.
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Affiliation(s)
- Piera Maccagnani
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e i Microsistemi, Via P. Gobetti 101, 40129 Bologna, Italy
- Department of Physics and Earth Sciences, University of Ferrara, Via Giuseppe Saragat 1/c, 44122 Ferrara, Italy
| | - Marco Pieruccini
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e i Microsistemi, Via P. Gobetti 101, 40129 Bologna, Italy
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5
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Jalil A, Zhao T, Firdous A, Kanwal A, Ali Raza SR, Rafiq A. Computational Insights into Schottky Barrier Heights: Graphene and Borophene Interfaces with H- and H́-XSi 2N 4 (X = Mo, W) Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:8463-8473. [PMID: 38591916 DOI: 10.1021/acs.langmuir.3c04045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The two-dimensional (2D) semiconducting family of XSi2N4 (X = Mo and W), an emergent class of air-stable monolayers, has recently gained attention due to its distinctive structural, mechanical, transport, and optical properties. However, the electrical contact between XSi2N4 and metals remains a mystery. In this study, we inspect the electronic and transport properties, specifically the Schottky barrier height (SBH) and tunneling probability, of XSi2N4-based van der Waals contacts by means of first-principles calculations. Our findings reveal that the electrical contacts of XSi2N4 with metals can serve as the foundation for nanoelectronic devices with ultralow SBHs. We further analyzed the tunneling probability of different metal contacts with XSi2N4. We found that the H-phase XSi2N4/metal contact shows superior tunneling probability compared to that of H́-based metal contacts. Our results suggest that heterostructures at interfaces can potentially enable efficient tunneling barrier modulation in metal contacts, particularly in the case of MoSi2N4/borophene compared to MoSi2N4/graphene and WSi2N4/graphene in transport-efficient electronic devices. Among the studied heterostructures, tunneling efficiency is highest at the H and H́-MoSi2N4/borophene interfaces, with barrier heights of 2.1 and 1.52 eV, respectively, and barrier widths of 1.04 and 0.8 Å. Furthermore, the tunneling probability for these interfaces was identified to be 21.3 and 36.4%, indicating a good efficiency of carrier injection. Thus, our study highlights the potential of MoSi2N4/borophene contact in designing power-efficient Ohmic devices.
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Affiliation(s)
- Abdul Jalil
- NPU-NCP Joint International Research Center on Advanced Nanomaterials & Defects Engineering, Shaanxi Engineering Laboratory for Graphene New Carbon Materials and Applications, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
| | - Tingkai Zhao
- NPU-NCP Joint International Research Center on Advanced Nanomaterials & Defects Engineering, Shaanxi Engineering Laboratory for Graphene New Carbon Materials and Applications, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
| | - Ammara Firdous
- Department of Physics, Allama Iqbal Open University, Sector H-8, Islamabad 44000, Pakistan
| | - Arooba Kanwal
- Department of Physics, Allama Iqbal Open University, Sector H-8, Islamabad 44000, Pakistan
| | - Syed Raza Ali Raza
- Department of Physics, Allama Iqbal Open University, Sector H-8, Islamabad 44000, Pakistan
| | - Aftab Rafiq
- Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Lehtrar Road, Islamabad 44000, Pakistan
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6
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Luo Y, Su T, Yang HY, Ang YS, Ang LK. Analytical Model of Optical-Field-Driven Subcycle Electron Tunneling Pulses from Two-Dimensional Materials. NANO LETTERS 2024; 24:3882-3889. [PMID: 38527217 DOI: 10.1021/acs.nanolett.3c04928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
We develop analytical models of optical-field-driven electron tunneling from the edge and surface of free-standing two-dimensional (2D) materials. We discover a universal scaling between the tunneling current density (J) and the electric field near the barrier (F): In(J/|F|β) ∝ 1/|F| with β values of 3/2 and 1 for edge emission and vertical surface emission, respectively. At ultrahigh values of F, the current density exhibits an unexpected high-field saturation effect due to the reduced dimensionality of the 2D material, which is absent in the traditional bulk material. Our calculation reveals the dc bias as an efficient method for modulating the optical-field tunneling subcycle emission characteristics. Importantly, our model is in excellent agreement with a recent experiment on graphene. Our results offer a useful framework for understanding optical-field tunneling emission from 2D materials, which are helpful for the development of optoelectronics and emerging petahertz vacuum nanoelectronics.
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Affiliation(s)
- Yi Luo
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Tong Su
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Hui Ying Yang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Yee Sin Ang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Lay Kee Ang
- Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
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7
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Guo X, Hu X, Zhang S, Yang J, Chen C, Zhang J, Qu H, Zhang S, Zhou W. High-Performance and Low-Power p-Channel Transistors Based on Monolayer Be 2C. ACS APPLIED MATERIALS & INTERFACES 2023; 15:53644-53650. [PMID: 37936317 DOI: 10.1021/acsami.3c09470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
The advantages of 2D materials in alleviating the issues of short-channel effect and power dissipation in field-effect transistors (FETs) are well recognized. However, the progress of complementary integrated circuits has been stymied by the absence of high-performance (HP) and low-power (LP) p-channel transistors. Therefore, we conducted an investigation into the electronic and ballistic transport characteristics of monolayer Be2C, which features quasi-planar hexacoordinate carbons, by employing nonequilibrium Green's function combined with density functional theory. Be2C monolayer has planar anticonventional bonds and a direct bandgap of 1.53 eV. The Ion of p-type Be2C HP FETs can achieve a remarkable 2767 μA μm-1. All of the device properties of 2D Be2C FETs can exceed the demands of the International Roadmap for Devices and Systems. The excellent properties of Be2C as a 2D p-orbital material with a high hole mobility are discussed from different aspects. Our findings thus illustrate the tremendous potential of 2D Be2C for the next generation of HP and LP electronics applications.
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Affiliation(s)
- Xinwei Guo
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Xuemin Hu
- School of Material Engineering, Jinling Institute of Technology, Nanjing 211169, P. R. China
| | - Shuyu Zhang
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Jialin Yang
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Chuyao Chen
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Jingwen Zhang
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Hengze Qu
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Shengli Zhang
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
| | - Wenhan Zhou
- MIIT Key Laboratory of Advanced Display Materials and Devices, College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
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8
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Liu G, Chen T, Zhou G, Xu Z, Xiao X. Nonvolatile Electrical Control and Reversible Gas Capture by Ferroelectric Polarization Switching in 2D FeI 2/In 2S 3 van der Waals Heterostructures. ACS Sens 2023; 8:1440-1449. [PMID: 36971553 DOI: 10.1021/acssensors.2c02365] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Nonvolatile electrical control is the core of future magnetoelectric nanodevices. In this work, we systematically explore both the electronic structures and transport properties of multiferroic van der Waals (vdW) heterostructures consisting of a ferromagnetic FeI2 monolayer and a ferroelectric In2S3 monolayer using density functional theory and the nonequilibrium Green's function method. The results reveal that the FeI2 monolayer can be reversibly switched between semiconducting and half-metallic properties by nonvolatile control of the In2S3 ferroelectric polarization states. Correspondingly, the proof-of-concept two-probe nanodevice based on the FeI2/In2S3 vdW heterostructure exhibits a significant valving effect by modulating the ferroelectric switching. Moreover, it is also found that the preference of nitrogen-containing gases such as NH3, NO, and NO2 for adsorption on the surface of FeI2/In2S3 vdW heterostructures strongly depends on the polarization direction of the ferroelectric layer. In particular, the FeI2/In2S3 heterostructure shows reversible capture behavior for NH3. As a result, the FeI2/In2S3 vdW heterostructure-based gas sensor demonstrates high selectivity and sensitivity. These findings may open up a new route for the application of multiferroic heterostructures to spintronics, nonvolatile memories, and gas sensors.
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Batool S, Idrees M, Han ST, Roy VAL, Zhou Y. Electrical Contacts With 2D Materials: Current Developments and Future Prospects. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206550. [PMID: 36587964 DOI: 10.1002/smll.202206550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Current electrical contact models are occasionally insufficient at the nanoscale owing to the wide variations in outcomes between 2D mono and multi-layered and bulk materials that result from their distinctive electrostatics and geometries. Contrarily, devices based on 2D semiconductors present a significant challenge due to the requirement for electrical contact with resistances close to the quantum limit. The next generation of low-power devices is already hindered by the lack of high-quality and low-contact-resistance contacts on 2D materials. The physics and materials science of electrical contact resistance in 2D materials-based nanoelectronics, interface configurations, charge injection mechanisms, and numerical modeling of electrical contacts, as well as the most pressing issues that need to be resolved in the field of research and development, will all be covered in this review.
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Affiliation(s)
- Saima Batool
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Muhammad Idrees
- Additive Manufacturing Institute, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Su-Ting Han
- College of Electronics Science & Technology, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Vellaisamy A L Roy
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Ye Zhou
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
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10
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Gao Y, Okada S. Field induced electron emission from graphene nanostructures. NANO EXPRESS 2022. [DOI: 10.1088/2632-959x/ac8822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Electric fields play a crucial role in modulating the electronic properties of nanoscale materials. Electron emission, induced by an electric field, is a representative phenomenon. Experimental and theoretical aspects of such electron emission from graphene are briefly reviewed. The emission occurs at the edge of graphene flakes, not at the surface, because the edge highly concentrates the electric field. Emission currents are sensitive to the edge shapes and edge functionalization. This review provides guiding principles for designing high-efficiency field-emission devices by using graphene nanostructures.
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11
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Pam ME, Li S, Su T, Chien YC, Li Y, Ang YS, Ang KW. Interface-Modulated Resistive Switching in Mo-Irradiated ReS 2 for Neuromorphic Computing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202722. [PMID: 35610176 DOI: 10.1002/adma.202202722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/30/2022] [Indexed: 06/15/2023]
Abstract
Coupling charge impurity scattering effects and charge-carrier modulation by doping can offer intriguing opportunities for atomic-level control of resistive switching (RS). Nonetheless, such effects have remained unexplored for memristive applications based on 2D materials. Here a facile approach is reported to transform an RS-inactive rhenium disulfide (ReS2 ) into an effective switching material through interfacial modulation induced by molybdenum-irradiation (Mo-i) doping. Using ReS2 as a model system, this study unveils a unique RS mechanism based on the formation/dissolution of metallic β-ReO2 filament across the defective ReS2 interface during the set/reset process. Through simple interfacial modulation, ReS2 of various thicknesses are switchable by modulating the Mo-irradiation period. Besides, the Mo-irradiated ReS2 (Mo-ReS2 ) memristor further exhibits a bipolar non-volatile switching ratio of nearly two orders of magnitude, programmable multilevel resistance states, and long-term synaptic plasticity. Additionally, the fabricated device can achieve a high MNIST learning accuracy of 91% under a non-identical pulse train. The study's findings demonstrate the potential for modulating RS in RS-inactive 2D materials via the unique doping-induced charged impurity scattering property.
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Affiliation(s)
- Mei Er Pam
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Sifan Li
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Tong Su
- Science, Mathematics and Technology (SMT), Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore, 487372, Singapore
| | - Yu-Chieh Chien
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Yesheng Li
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Yee Sin Ang
- Science, Mathematics and Technology (SMT), Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore, 487372, Singapore
| | - Kah-Wee Ang
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
- Institute of Materials Research and Engineering, A*STAR, 2 Fusionopolis, Singapore, 138634, Singapore
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12
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Jiang H, Li B, Wei Y, Feng S, Di Z, Xue Z, Sun D, Liu C. High-performance gold/graphene/germanium photodetector based on a graphene-on-germanium wafer. NANOTECHNOLOGY 2022; 33:345204. [PMID: 35576894 DOI: 10.1088/1361-6528/ac6ff0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/15/2022] [Indexed: 06/15/2023]
Abstract
The metal/germanium (Ge) photodetectors have attracted much attention for their potential applications in on-chip optoelectronics. One critical issue is the relatively large dark current due to the limited Schottky potential barrier height of the metal/germanium junction, which is mainly caused by the small bandgap of Ge and the Fermi energy level pinning effect between the metal and Ge. The main technique to solve this problem is to insert a thin interlayer between the metal and Ge. However, so far, the dark current of the photodetectors is still large when using a bulk-material insertion layer, while when using a two-dimensional insertion layer, the area of the insertion layer is too small to support a mass production. Here, we report a gold/graphene/germanium photodetector with a wafer-scale graphene insertion layer using a 4 inch graphene-on-germanium wafer. The insertion layer significantly increases the potential barrier height, leading to a dark current as low as 1.6 mA cm-2, and a responsivity of 1.82 A W-1which are the best results for metal/Ge photodetectors reported so far. Our work contributes to the mass production of high-performance metal/Ge photodetectors.
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Affiliation(s)
- Haiyan Jiang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
- School of Material Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
| | - Bo Li
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
- School of Material Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
| | - Yuning Wei
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
- School of Material Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
| | - Shun Feng
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
| | - Zengfeng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, People's Republic of China
| | - Zhongying Xue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, People's Republic of China
| | - Dongming Sun
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
- School of Material Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
| | - Chi Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
- School of Material Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, People's Republic of China
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13
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Lau CS, Chee JY, Cao L, Ooi ZE, Tong SW, Bosman M, Bussolotti F, Deng T, Wu G, Yang SW, Wang T, Teo SL, Wong CPY, Chai JW, Chen L, Zhang ZM, Ang KW, Ang YS, Goh KEJ. Gate-Defined Quantum Confinement in CVD 2D WS 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2103907. [PMID: 34437744 DOI: 10.1002/adma.202103907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/19/2021] [Indexed: 06/13/2023]
Abstract
Temperature-dependent transport measurements are performed on the same set of chemical vapor deposition (CVD)-grown WS2 single- and bilayer devices before and after atomic layer deposition (ALD) of HfO2 . This isolates the influence of HfO2 deposition on low-temperature carrier transport and shows that carrier mobility is not charge impurity limited as commonly thought, but due to another important but commonly overlooked factor: interface roughness. This finding is corroborated by circular dichroic photoluminescence spectroscopy, X-ray photoemission spectroscopy, cross-sectional scanning transmission electron microscopy, carrier-transport modeling, and density functional modeling. Finally, electrostatic gate-defined quantum confinement is demonstrated using a scalable approach of large-area CVD-grown bilayer WS2 and ALD-grown HfO2 . The high dielectric constant and low leakage current enabled by HfO2 allows an estimated quantum dot size as small as 58 nm. The ability to lithographically define increasingly smaller devices is especially important for transition metal dichalcogenides due to their large effective masses, and should pave the way toward their use in quantum information processing applications.
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Affiliation(s)
- Chit Siong Lau
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Jing Yee Chee
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Liemao Cao
- Science, Mathematics and Technology, Singapore University of Technology, 8 Somapah Road, Singapore, 487372, Singapore
| | - Zi-En Ooi
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Shi Wun Tong
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Michel Bosman
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Fabio Bussolotti
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Tianqi Deng
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore, 138632, Singapore
| | - Gang Wu
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore, 138632, Singapore
| | - Shuo-Wang Yang
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore, 138632, Singapore
| | - Tong Wang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Siew Lang Teo
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Calvin Pei Yu Wong
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Jian Wei Chai
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Li Chen
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Zhong Ming Zhang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Kah-Wee Ang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Yee Sin Ang
- Science, Mathematics and Technology, Singapore University of Technology, 8 Somapah Road, Singapore, 487372, Singapore
| | - Kuan Eng Johnson Goh
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore, 138634, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
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14
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Pham PV, Bodepudi SC, Shehzad K, Liu Y, Xu Y, Yu B, Duan X. 2D Heterostructures for Ubiquitous Electronics and Optoelectronics: Principles, Opportunities, and Challenges. Chem Rev 2022; 122:6514-6613. [PMID: 35133801 DOI: 10.1021/acs.chemrev.1c00735] [Citation(s) in RCA: 82] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A grand family of two-dimensional (2D) materials and their heterostructures have been discovered through the extensive experimental and theoretical efforts of chemists, material scientists, physicists, and technologists. These pioneering works contribute to realizing the fundamental platforms to explore and analyze new physical/chemical properties and technological phenomena at the micro-nano-pico scales. Engineering 2D van der Waals (vdW) materials and their heterostructures via chemical and physical methods with a suitable choice of stacking order, thickness, and interlayer interactions enable exotic carrier dynamics, showing potential in high-frequency electronics, broadband optoelectronics, low-power neuromorphic computing, and ubiquitous electronics. This comprehensive review addresses recent advances in terms of representative 2D materials, the general fabrication methods, and characterization techniques and the vital role of the physical parameters affecting the quality of 2D heterostructures. The main emphasis is on 2D heterostructures and 3D-bulk (3D) hybrid systems exhibiting intrinsic quantum mechanical responses in the optical, valley, and topological states. Finally, we discuss the universality of 2D heterostructures with representative applications and trends for future electronics and optoelectronics (FEO) under the challenges and opportunities from physical, nanotechnological, and material synthesis perspectives.
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Affiliation(s)
- Phuong V Pham
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Srikrishna Chanakya Bodepudi
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Khurram Shehzad
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Yuan Liu
- School of Physics and Electronics, Hunan University, Hunan 410082, China
| | - Yang Xu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Bin Yu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, California 90095-1569, United States
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15
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Garg S, Fix JP, Krayev AV, Flanery C, Colgrove M, Sulkanen AR, Wang M, Liu GY, Borys NJ, Kung P. Nanoscale Raman Characterization of a 2D Semiconductor Lateral Heterostructure Interface. ACS NANO 2022; 16:340-350. [PMID: 34936762 DOI: 10.1021/acsnano.1c06595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The nature of the interface in lateral heterostructures of 2D monolayer semiconductors including its composition, size, and heterogeneity critically impacts the functionalities it engenders on the 2D system for next-generation optoelectronics. Here, we use tip-enhanced Raman scattering (TERS) to characterize the interface in a single-layer MoS2/WS2 lateral heterostructure with a spatial resolution of 50 nm. Resonant and nonresonant TERS spectroscopies reveal that the interface is alloyed with a size that varies over an order of magnitude─from 50 to 600 nm─within a single crystallite. Nanoscale imaging of the continuous interfacial evolution of the resonant and nonresonant Raman spectra enables the deconvolution of defect activation, resonant enhancement, and material composition for several vibrational modes in single-layer MoS2, MoxW1-xS2, and WS2. The results demonstrate the capabilities of nanoscale TERS spectroscopy to elucidate macroscopic structure-property relationships in 2D materials and to characterize lateral interfaces of 2D systems on length scales that are imperative for devices.
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Affiliation(s)
- Sourav Garg
- Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - J Pierce Fix
- Department of Physics, Montana State University, Bozeman, Montana 59717, United States
| | | | - Connor Flanery
- Department of Physics, Montana State University, Bozeman, Montana 59717, United States
| | - Michael Colgrove
- Department of Physics, Montana State University, Bozeman, Montana 59717, United States
| | - Audrey R Sulkanen
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Minyuan Wang
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Gang-Yu Liu
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Nicholas J Borys
- Department of Physics, Montana State University, Bozeman, Montana 59717, United States
| | - Patrick Kung
- Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
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16
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Hu X, Liu W, Yang J, Zhang S, Ye Y. First-principles study on the electronic structures and contact properties of graphene/XC (X = P, As, Sb, and Bi) van der Waals heterostructures. Phys Chem Chem Phys 2021; 23:25136-25142. [PMID: 34729574 DOI: 10.1039/d1cp03850h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electrical contacts at the van der Waals (vdW) interface between two-dimensional (2D) semiconductors and metal electrodes could dramatically affect the device performance. Herein, we construct a series of graphene (Gr)/XC (X = P, As, Sb, and Bi) vdW heterostructures, in which XC monolayers have aroused considerable attention recently as an emerging class of 2D semiconductors. The electronic structures and contact properties of Gr/XC vdW heterostructures are investigated systematically using first-principles calculations. The band structures indicate that both Gr/PC and Gr/AsC heterostructures form n-type Schottky contacts with Schottky barrier heights (SBHs) of 0.01 eV and 0.43 eV, respectively, while both Gr/SbC and Gr/BiC heterostructures preferably form Ohmic contacts. The different X atoms result in different work functions, electron flows, charge distributions and orientations of the dipole moment in Gr/XC heterostructures. Moreover, the tunneling probabilities increase with the increasing atom radius of X from P to Bi, indicating the most improved current and smaller contact resistance at the interfaces of Gr/BiC compared to Gr/PC, Gr/AsC and Gr/SbC heterostructures. Our work could provide meaningful information for designing high-performance nanoelectronic devices based on Gr/XC heterostructures.
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Affiliation(s)
- Xuemin Hu
- School of Material Engineering, Jinling Institute of Technology, Nanjing 211169, China.
| | - Wenqiang Liu
- MIIT Key Laboratory of Advanced Display Materials and Devices, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Jialin Yang
- MIIT Key Laboratory of Advanced Display Materials and Devices, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Shengli Zhang
- MIIT Key Laboratory of Advanced Display Materials and Devices, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. .,National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
| | - Yuanfeng Ye
- School of Material Engineering, Jinling Institute of Technology, Nanjing 211169, China.
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17
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Zhang X, Sin Ang Y, Ang LK, Chen J. Concentrated thermionic solar cells using graphene as the collector: theoretical efficiency limit and design rules. NANOTECHNOLOGY 2021; 33:065404. [PMID: 34710863 DOI: 10.1088/1361-6528/ac3459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
We propose an updated design on concentrated thermionic emission solar cells, which demonstrates a high solar-to-electricity energy conversion efficiency larger than 10% under 600 suns, by harnessing the exceptional electrical, thermal, and radiative properties of the graphene as a collector electrode. By constructing an analytical model that explicitly takes into account the non-Richardson behavior of the thermionic emission current from graphene, space charge effect in vacuum gap, and the various irreversible energy losses within the subcomponents, we perform detailed characterizations on the conversion efficiency limit and parametric optimum design of the proposed system. Under 800 suns, a maximum efficiency of 12.8% has been revealed, where current density is 3.87 A cm-2, output voltage is 1.76 V, emitter temperature is 1707 K, and collector temperature is 352 K. Moreover, we systematically compare the peak efficiencies of various configurations combining diamond or graphene, and show that utilizing diamond films as an emitter and graphene as a collector offers the highest conversion efficiency, thus revealing the important role of graphene in achieving high-performance thermionic emission solar cells. This work thus opens up new avenues to advance the efficiency limit of thermionic solar energy conversion and the development of next-generation novel-nanomaterial-based solar energy harvesting technology.
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Affiliation(s)
- Xin Zhang
- School of Science, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Yee Sin Ang
- Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Lay Kee Ang
- Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Jincan Chen
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
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18
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Investigation of the Photon to Charge Conversion and Its Implication on Photovoltaic Cell Efficient Operation. ENERGIES 2021. [DOI: 10.3390/en14113022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Efficient photon to charge (PTC) transfer is considered to be the cornerstone of technological improvements in the photovoltaic (PV) industry, while it constitutes the most common process in nature. This study aims to investigate the parameters that impact efficient PV-cell photon to charge conversion in two ways: (a) providing a brief research analysis to extract the key features which affect the electrical and optical performance of PV cells’ operation, and (b) investigating the dependance of these characteristics on the photon to charge mechanisms. The former direction focuses on the latest advances regarding the impacts of the microenvironment climate conditions on the PV module and its operational performance, while the latter examines the fundamental determinants of the cell’s efficient operation. The electrical and optical parameters of the bulk PV cells are influenced by both the external microenvironment and the intrinsic photon to charge conversion principles. Light and energy harvesting issues need to be overcome, while nature-inspired interpretation and mimicking of photon to charge and excitation energy transfer are in an infant stage, furthering a better understanding of artificial photosynthesis. A future research orientation is proposed which focuses on scaling up development and making use of the before mentioned challenges.
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19
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Massicotte M, Soavi G, Principi A, Tielrooij KJ. Hot carriers in graphene - fundamentals and applications. NANOSCALE 2021; 13:8376-8411. [PMID: 33913956 PMCID: PMC8118204 DOI: 10.1039/d0nr09166a] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/30/2021] [Indexed: 05/15/2023]
Abstract
Hot charge carriers in graphene exhibit fascinating physical phenomena, whose understanding has improved greatly over the past decade. They have distinctly different physical properties compared to, for example, hot carriers in conventional metals. This is predominantly the result of graphene's linear energy-momentum dispersion, its phonon properties, its all-interface character, and the tunability of its carrier density down to very small values, and from electron- to hole-doping. Since a few years, we have witnessed an increasing interest in technological applications enabled by hot carriers in graphene. Of particular interest are optical and optoelectronic applications, where hot carriers are used to detect (photodetection), convert (nonlinear photonics), or emit (luminescence) light. Graphene-enabled systems in these application areas could find widespread use and have a disruptive impact, for example in the field of data communication, high-frequency electronics, and industrial quality control. The aim of this review is to provide an overview of the most relevant physics and working principles that are relevant for applications exploiting hot carriers in graphene.
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Affiliation(s)
- Mathieu Massicotte
- Institut Quantique and Département de Physique, Université de SherbrookeSherbrookeQuébecCanada
| | - Giancarlo Soavi
- Institute of Solid State Physics, Friedrich Schiller University Jena07743 JenaGermany
- Abbe Center of Photonics, Friedrich Schiller University Jena07745 JenaGermany
| | | | - Klaas-Jan Tielrooij
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB08193BellaterraBarcelonaSpain
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20
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Lv L, Yu J, Hu M, Yin S, Zhuge F, Ma Y, Zhai T. Design and tailoring of two-dimensional Schottky, PN and tunnelling junctions for electronics and optoelectronics. NANOSCALE 2021; 13:6713-6751. [PMID: 33885475 DOI: 10.1039/d1nr00318f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Owing to their superior carrier mobility, strong light-matter interactions, and flexibility at the atomically thin thickness, two-dimensional (2D) materials are attracting wide interest for application in electronic and optoelectronic devices, including rectifying diodes, transistors, memory, photodetectors, and light-emitting diodes. At the heart of these devices, Schottky, PN, and tunneling junctions are playing an essential role in defining device function. Intriguingly, the ultrathin thickness and unique van der Waals (vdW) interlayer coupling in 2D materials has rendered enormous opportunities for the design and tailoring of various 2D junctions, e.g. using Lego-like hetero-stacking, surface decoration, and field-effect modulation methods. Such flexibility has led to marvelous breakthroughs during the exploration of 2D electronics and optoelectronic devices. To advance further, it is imperative to provide an overview of existing strategies for the engineering of various 2D junctions for their integration in the future. Thus, in this review, we provide a comprehensive survey of previous efforts toward 2D Schottky, PN, and tunneling junctions, and the functional devices built from them. Though these junctions exhibit similar configurations, distinct strategies have been developed for their optimal figures of merit based on their working principles and functional purposes.
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Affiliation(s)
- Liang Lv
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
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21
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Folorunso O, Hamam Y, Sadiku R, Ray SS. Computational Study of Graphene-Polypyrrole Composite Electrical Conductivity. NANOMATERIALS 2021; 11:nano11040827. [PMID: 33804929 PMCID: PMC8063847 DOI: 10.3390/nano11040827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 03/20/2021] [Indexed: 11/16/2022]
Abstract
In this study, the electrical properties of graphene–polypyrrole (graphene-PPy) nanocomposites were thoroughly investigated. A numerical model, based on the Simmons and McCullough equations, in conjunction with the Monte Carlo simulation approach, was developed and used to analyze the effects of the thickness of the PPy, aspect ratio diameter of graphene nanorods, and graphene intrinsic conductivity on the transport of electrons in graphene–PPy–graphene regions. The tunneling resistance is a critical factor determining the transport of electrons in composite devices. The junction capacitance of the composite was predicted. A composite with a large insulation thickness led to a poor electrochemical electrode. The dependence of the electrical conductivity of the composite on the volume fraction of the filler was studied. The results of the developed model are consistent with the percolation theory and measurement results reported in literature. The formulations presented in this study can be used for optimization, prediction, and design of polymer composite electrical properties.
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Affiliation(s)
- Oladipo Folorunso
- Department of Electrical Engineering, French South African Institute of Technology (F’SATI), Tshwane University of Technology, Pretoria 0001, South Africa;
- Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, Pretoria 0001, South Africa
- Correspondence: (O.F.); or (S.S.R.)
| | - Yskandar Hamam
- Department of Electrical Engineering, French South African Institute of Technology (F’SATI), Tshwane University of Technology, Pretoria 0001, South Africa;
- École Supérieure d’Ingénieurs en Électrotechnique et Électronique, Cité Descartes, 2 Boulevard Blaise Pascal, Noisy-le-Grand, 93160 Paris, France
| | - Rotimi Sadiku
- Department of Chemical, Institute of NanoEngineering Research (INER), Metallurgy and Material Engineering, Tshwane University of Technology, Pretoria 0001, South Africa;
| | - Suprakas Sinha Ray
- Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, Pretoria 0001, South Africa
- Department of Chemical Sciences, University of Johannesburg, Doornfontein, Johannesburg 2028, South Africa
- Correspondence: (O.F.); or (S.S.R.)
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22
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Jelver L, Stradi D, Stokbro K, Jacobsen KW. Schottky barrier lowering due to interface states in 2D heterophase devices. NANOSCALE ADVANCES 2021; 3:567-574. [PMID: 36131736 PMCID: PMC9418679 DOI: 10.1039/d0na00795a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/05/2020] [Indexed: 05/03/2023]
Abstract
The Schottky barrier of a metal-semiconductor junction is one of the key quantities affecting the charge transport in a transistor. The Schottky barrier height depends on several factors, such as work function difference, local atomic configuration in the interface, and impurity doping. We show that also the presence of interface states at 2D metal-semiconductor junctions can give rise to a large renormalization of the effective Schottky barrier determined from the temperature dependence of the current. We investigate the charge transport in n- and p-doped monolayer MoTe2 1T'-1H junctions using ab initio quantum transport calculations. The Schottky barriers are extracted both from the projected density of states and the transmission spectrum, and by simulating the IT-characteristic and applying the thermionic emission model. We find interface states originating from the metallic 1T' phase rather than the semiconducting 1H phase in contrast to the phenomenon of Fermi level pinning. Furthermore, we find that these interface states mediate large tunneling currents which dominates the charge transport and can lower the effective barrier to a value of only 55 meV.
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Affiliation(s)
- Line Jelver
- CAMD, Dept. of Physics, Technical University of Denmark Bldg. 309 DK-2800 Kongens Lyngby Denmark
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Daniele Stradi
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Kurt Stokbro
- Synopsys QuantumATK Fruebjergvej 3, PostBox 4 DK-2100 Copenhagen Denmark
| | - Karsten Wedel Jacobsen
- CAMD, Dept. of Physics, Technical University of Denmark Bldg. 309 DK-2800 Kongens Lyngby Denmark
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23
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Bafekry A, Faraji M, Abdollahzadeh Ziabari A, Fadlallah MM, Nguyen CV, Ghergherehchi M, Feghhi SAH. A van der Waals heterostructure of MoS2/MoSi2N4: a first-principles study. NEW J CHEM 2021. [DOI: 10.1039/d1nj00344e] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Motivated by the successful preparation of MoSi2N4 monolayers in the last year [Y.-L. Hong et al., Science, 2020, 369, 670–674], the structural, electronic and optical properties of MoS2/MoSi2N4 heterostructure are investigated.
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Affiliation(s)
- A. Bafekry
- Department of Radiation Application
- Shahid Beheshti University
- Tehran
- Iran
- Department of Physics
| | - M. Faraji
- Micro and Nanotechnology Graduate Program
- TOBB University of Economics and Technology
- Ankara
- Turkey
| | | | - M. M. Fadlallah
- Department of Physics
- Faculty of Science
- Benha University
- 13518 Benha
- Egypt
| | - Chuong V. Nguyen
- Department of Materials Science and Engineering
- Le Quy Don Technical University
- Hanoi 100000
- Vietnam
| | - M. Ghergherehchi
- College of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon
- Korea
| | - S. A. H. Feghhi
- Department of Radiation Application
- Shahid Beheshti University
- Tehran
- Iran
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Li M, Lan F, Yang W, Ji Z, Zhang Y, Xi N, Xin X, Jin X, Li G. Influence of MoS 2-metal interface on charge injection: a comparison between various metal contacts. NANOTECHNOLOGY 2020; 31:395713. [PMID: 32662448 DOI: 10.1088/1361-6528/ab9cf6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Achieving good contacts is vital for harnessing the fascinating properties of two-dimensional (2D) materials. However, unsatisfactory 2D material-metal interfaces remain a problem that hinders the successful application of 2D materials for fabricating nanodevices. In this study, Kelvin probe force microscopy (KPFM) and other high-resolution microscopy techniques are utilized to characterize the surface morphology and contact interface between MoS2 and common metals including Au, Ti, Pd, and Ni. Surface potential information, including the contact potential difference ([Formula: see text]) and surface potential difference ([Formula: see text]) of each MoS2-metal contact, is obtained. By comparing the surface potential distribution mappings with and without illumination, non-zero surface photovoltage (SPV) values and evident shift with amplitudes of 32 mV and 44 mV are observed for MoS2-Au and Ti, but not for MoS2-Pd and Ni. The Schottky barrier heights of MoS2-Au, Ti, Pd, and Ni are roughly evaluated from their I-V curves. Raman spectroscopy is also carried out to ensure more convincing results. All the results suggest that a smoother MoS2-metal interface results in better charge transport behaviors. Our analysis of the underlying mechanism and experimental findings offer a new perspective to better understand MoS2-metal contacts and underscore the fundamental importance of interface morphology for MoS2-based devices.
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Affiliation(s)
- Meng Li
- College of Information Science and Engineering, Shenyang University of Technology, Shenyang, People's Republic of China. State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, People's Republic of China
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25
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Cao L, Wu Q, Ang YS, Ang LK. Tunable band alignment in boron carbon nitride and blue phosphorene van der Waals heterostructure. NANO EXPRESS 2020. [DOI: 10.1088/2632-959x/aba9a9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
The hybrid monolayer of boron nitride and graphene, namely the BC
x
N monolayer, has been recently revealed as a direct bandgap semiconductor with exceptional thermal, mechanical and optical properties. The integration of such monolayer with other 2D materials into a van der Waals heterostructure (VDWH), however, remains largely unexplored thus far. In this work, we investigate the electronic and structural properties of a new class of VDWH obtained via the vertical stacking of BC
x
N (x = 2, 6) and blue phosphorene monolayers. By using first-principle density functional theory (DFT) simulation, we show that BC
x
N couples to the blue phosphorene layer via weak van der Waals interactions and exhibits a type-II band alignment which is beneficial for electron-hole pair separation in photodetection and solar cell applications. Intriguingly, changing the interlayer separation induces a indirect-to-direct band gap transition which changes the band alignment types of the VDWH. The interlayer separation, which can be readily tuned via a vertical strain, thus provides a useful tuning knob for switching the heterostructures between type-I and type-II VDWHs. Our findings reveals the BC
x
N-based VDWH as a versatile material platform with tunable band alignments, thus opening a route towards novel VDWH-based optoelectronic devices.
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26
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Canton-Vitoria R, Hotta T, Liu Z, Inoue T, Kitaura R. Stabilization of metallic phases through formation of metallic/semiconducting lateral heterostructures. J Chem Phys 2020; 153:084702. [PMID: 32872864 DOI: 10.1063/5.0012782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this study, we develop a new approach for stabilization of metallic phases of monolayer MoS2 through the formation of lateral heterostructures composed of semiconducting/metallic MoS2. The structure of metallic (a mixture of T and T') and semiconducting (2H) phases was unambiguously characterized by Raman spectroscopy, x-ray photoelectron spectroscopy, photoluminescence imaging, and transmission electron microscope observations. The amount of NaCl, reaction temperature, reaction time, and locations of substrates are essential for controlling the percentage of metallic/semiconducting phases in lateral heterostructures; loading a large amount of NaCl at low temperatures with short reaction times prefers metallic phases. The existence of the semiconducting phase in MoS2 lateral heterostructures significantly enhances the stability of the metallic phases through passivation of reactive edges. The same approach can be applied to other transition metal dichalcogenides (TMDs), such as WS2, leading to boosting of basic research and application of TMDs in metallic phases.
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Affiliation(s)
| | - Takato Hotta
- Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan
| | - Zheng Liu
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
| | - Tsukasa Inoue
- Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan
| | - Ryo Kitaura
- Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan
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27
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Xiong X, Zhou Y, Luo Y, Li X, Bosman M, Ang LK, Zhang P, Wu L. Plasmon-Enhanced Resonant Photoemission Using Atomically Thick Dielectric Coatings. ACS NANO 2020; 14:8806-8815. [PMID: 32567835 DOI: 10.1021/acsnano.0c03406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
By proposing an atomically thick dielectric coating on a metal nanoemitter, we theoretically show that the optical field tunneling of ultrafast-laser-induced photoemission can occur at an ultralow incident field strength of 0.03 V/nm. This coating strongly confines plasmonic fields and provides secondary field enhancement beyond the geometrical plasmon field enhancement effect, which can substantially reduce the barrier and enable more efficient photoemission. We numerically demonstrate that a 1 nm thick layer of SiO2 around a Au-nanopyramid will enhance the resonant photoemission current density by 2 orders of magnitude, where the transition from multiphoton absorption to optical field tunneling is accessed at an incident laser intensity at least 10 times lower than that of the bare nanoemitter. The effects of the coating properties such as refractive index, thickness, and geometrical settings are studied, and tunable photoemission is numerically demonstrated by using different ultrafast lasers. Our approach can also directly be extended to nonmetal emitters, to-for example-2D material coatings, and to plasmon-induced hot carrier generation.
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Affiliation(s)
- Xiao Xiong
- Institute of High Performance Computing, Agency for Science, Technology, and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632
| | - Yang Zhou
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824-1226, United States
| | - Yi Luo
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824-1226, United States
| | - Xiang Li
- Leadmicro Nano Technology Co., Ltd, 7 Xingchuang Road, Wuxi 214000, China
| | - Michel Bosman
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634
| | - Lay Kee Ang
- SUTD-MIT International Design Center, Science, Mathematics and Technology Cluster, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372
| | - Peng Zhang
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824-1226, United States
| | - Lin Wu
- Institute of High Performance Computing, Agency for Science, Technology, and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632
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28
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Liang SJ, Cheng B, Cui X, Miao F. Van der Waals Heterostructures for High-Performance Device Applications: Challenges and Opportunities. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903800. [PMID: 31608514 DOI: 10.1002/adma.201903800] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/22/2019] [Indexed: 06/10/2023]
Abstract
The discovery of two-dimensional (2D) materials with unique electronic, superior optoelectronic, or intrinsic magnetic order has triggered worldwide interest in the fields of material science, condensed matter physics, and device physics. Vertically stacking 2D materials with distinct electronic and optical as well as magnetic properties enables the creation of a large variety of van der Waals heterostructures. The diverse properties of the vertical heterostructures open unprecedented opportunities for various kinds of device applications, e.g., vertical field-effect transistors, ultrasensitive infrared photodetectors, spin-filtering devices, and so on, which are inaccessible in conventional material heterostructures. Here, the current status of vertical heterostructure device applications in vertical transistors, infrared photodetectors, and spintronic memory/transistors is reviewed. The relevant challenges for achieving high-performance devices are presented. An outlook into the future development of vertical heterostructure devices with integrated electronic and optoelectronic as well as spintronic functionalities is also provided.
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Affiliation(s)
- Shi-Jun Liang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Bin Cheng
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Xinyi Cui
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210046, China
| | - Feng Miao
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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29
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de Andrade Deus DP, de Oliveira ISS. Tuning the Schottky barrier height in graphene/monolayer-GeI 2van der Waals heterostructure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:355501. [PMID: 32320968 DOI: 10.1088/1361-648x/ab8bf8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
We use first-principles simulations to investigate the structural and electronic properties of a heterostructure formed by graphene and monolayer GeI2(m-GeI2). While graphene has been extensively studied in the last 15 years, m-GeI2has been recently proposed to be a stable 2D semiconductor with a wide-band gap, Liuet al(2018J. Phys. Chem.C12222137). By staking both structures we obtain a metal-semiconductor junction, with great potential for applications in the designing of new (opto)electronic devices. The results show that the graphene Dirac cone is preserved in the graphene/m-GeI2heterostructure. We find that there are no chemical bonds at the graphene and m-GeI2interface, thus the heterostructure interactions are ruled by van der Waals (vdW) forces. The interface between graphene and m-GeI2results in a n-type Schottky contact. Furthermore, we show that a transition from n-type to p-type Schottky contact can be obtained by decreasing the interlayer distance. We also modulated the Schottky barrier heights by applying a perpendicular external electric field through the vdW heterostructure. In particular, positive values resulted in an increase of the n-type Schottky barrier height, while negative electric field values induced a transition from n-type to p-type Schottky contact. From our results, we show that m-GeI2is an interesting material to design new electronic Schottky devices based on graphene vdW heterostructures.
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Affiliation(s)
- D P de Andrade Deus
- Instituto Federal de Educação, Ciência e Tecnologia de Goiás, Departamento de Áreas Acadêmicas, Campus Jataí, 775 Orminda Vieira de Freitas, Jataí, GO, Brazil
| | - I S S de Oliveira
- Departamento de Física, Universidade Federal de Lavras, C.P. 3037, 37200-000, Lavras, MG, Brazil
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30
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Grillo A, Di Bartolomeo A, Urban F, Passacantando M, Caridad JM, Sun J, Camilli L. Observation of 2D Conduction in Ultrathin Germanium Arsenide Field-Effect Transistors. ACS APPLIED MATERIALS & INTERFACES 2020; 12:12998-13004. [PMID: 32100522 PMCID: PMC7997104 DOI: 10.1021/acsami.0c00348] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We report the fabrication and electrical characterization of germanium arsenide (GeAs) field-effect transistors with ultrathin channels. The electrical transport is investigated in the 20-280 K temperature range, revealing that the p-type electrical conductivity and the field-effect mobility are growing functions of temperature. An unexpected peak is observed in the temperature dependence of the carrier density per area at ∼75 K. Such a feature is explained considering that the increased carrier concentration at higher temperatures and the vertical band bending combined with the gate field lead to the formation of a two-dimensional (2D) conducting channel, limited to few interfacial GeAs layers, which dominates the channel conductance. The conductivity follows the variable-range hopping model at low temperatures and becomes the band-type at higher temperatures when the 2D channel is formed. The formation of the 2D channel is validated through a numerical simulation that shows excellent agreement with the experimental data.
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Affiliation(s)
- Alessandro Grillo
- Physics Department
“E. R. Caianiello”, University
of Salerno, via Giovanni Paolo II n. 132, Fisciano 84084, Italy
- CNR-SPIN
Salerno, via Giovanni
Paolo II n. 132, Fisciano 84084, Italy
| | - Antonio Di Bartolomeo
- Physics Department
“E. R. Caianiello”, University
of Salerno, via Giovanni Paolo II n. 132, Fisciano 84084, Italy
- CNR-SPIN
Salerno, via Giovanni
Paolo II n. 132, Fisciano 84084, Italy
| | - Francesca Urban
- Physics Department
“E. R. Caianiello”, University
of Salerno, via Giovanni Paolo II n. 132, Fisciano 84084, Italy
- CNR-SPIN
Salerno, via Giovanni
Paolo II n. 132, Fisciano 84084, Italy
| | - Maurizio Passacantando
- Department of Physical
and Chemical Science, University of L’Aquila
and CNR-SPIN L’Aquila, via Vetoio, L’Aquila 67100, Coppito, Italy
| | - Jose M. Caridad
- Department of Physics, Technical University
of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark
| | - Jianbo Sun
- Department of Physics, Technical University
of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark
| | - Luca Camilli
- Department of Physics, Technical University
of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark
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31
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Liang BW, Huang CC, Chao SP, Kao KJ, Simbulan KB, Lan YW, Kuan CH. Responsivity and detectivity enhancements by graphene overlay on normal-incident multicolor quantum grid infrared photodetectors. OPTICS EXPRESS 2020; 28:2456-2465. [PMID: 32121935 DOI: 10.1364/oe.384379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/08/2020] [Indexed: 06/10/2023]
Abstract
An efficient and effective method to achieve high responsivity and specific detectivity, particularly for normal-incident quantum well infrared photodetectors (QWIPs), is proposed in this study. By combining superlattice (SL) structure, grating structures, and graphene monolayer onto traditional QWIP designs, a graphene-covered multicolor quantum grid infrared photodetector (QGIP) with improved optoelectrical properties is developed. The enhancements of the device's responsivity and specific detectivity are about 7-fold and 20-fold, respectively, which resulted from an increase in the charge depletion region and the generation of extra photoelectrons due to graphene-semiconductor heterojunction. This method provides a potential candidate for future high-performance photodetectors.
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32
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Artificial 2D van der Waals Synapse Devices via Interfacial Engineering for Neuromorphic Systems. NANOMATERIALS 2020; 10:nano10010088. [PMID: 31906481 PMCID: PMC7022853 DOI: 10.3390/nano10010088] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/28/2019] [Accepted: 12/31/2019] [Indexed: 01/21/2023]
Abstract
Despite extensive investigations of a wide variety of artificial synapse devices aimed at realizing a neuromorphic hardware system, the identification of a physical parameter that modulates synaptic plasticity is still required. In this context, a novel two-dimensional architecture consisting of a NbSe2/WSe2/Nb2O5 heterostructure placed on an SiO2/p+ Si substrate was designed to overcome the limitations of the conventional silicon-based complementary metal-oxide semiconductor technology. NbSe2, WSe2, and Nb2O5 were used as the metal electrode, active channel, and conductance-modulating layer, respectively. Interestingly, it was found that the post-synaptic current was successfully modulated by the thickness of the interlayer Nb2O5, with a thicker interlayer inducing a higher synapse spike current and a stronger interaction in the sequential pulse mode. Introduction of the Nb2O5 interlayer can facilitate the realization of reliable and controllable synaptic devices for brain-inspired integrated neuromorphic systems.
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33
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A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts. Sci Rep 2019; 9:14484. [PMID: 31597925 PMCID: PMC6785565 DOI: 10.1038/s41598-019-50934-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 09/23/2019] [Indexed: 11/08/2022] Open
Abstract
Contact resistance and current crowding are important to nanoscale electrical contacts. In this paper, we present a self-consistent model to characterize partially overlapped parallel contacts with varying specific contact resistivity along the contact length. For parallel tunneling contacts formed between contacting members separated by a thin insulating gap, we examine the local voltage-dependent variation of potential barrier height and tunneling current along the contact length, by solving the lumped circuit transmission line model (TLM) equations coupled with the tunneling current self consistently. The current and voltage distribution along the parallel tunneling contacts and their overall contact resistance are analyzed in detail, for various input voltage, electrical contact dimension, and material properties (i.e. work function, sheet resistance of the contact members, and permittivity of the insulating layer). It is found the existing one-dimensional (1D) tunneling junction models become less reliable when the tunneling layer thickness becomes smaller or the applied voltage becomes larger. In these regimes, the proposed self-consistent model may provide a more accurate evaluation of the parallel tunneling contacts. For the special case of constant ohmic specific contact resistivity along the contact length, our theory has been spot-checked with finite element method (FEM) based numerical simulations. This work provides insights on the design, and potential engineering, of nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry.
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34
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Madas S, Mishra SK, Kahaly S, Kahaly MU. Superior Photo-thermionic electron Emission from Illuminated Phosphorene Surface. Sci Rep 2019; 9:10307. [PMID: 31312007 PMCID: PMC6635392 DOI: 10.1038/s41598-019-44823-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/14/2019] [Indexed: 11/28/2022] Open
Abstract
This work demonstrates that black phosphorene, a two dimensional allotrope of phosphorus, has the potential to be an efficient photo-thermionic emitter. To investigate and understand the novel aspects we use a combined approach in which ab initio quantum simulation tools are utilized along with semiclassical description for the emission process. First by using density functional theory based formalism, we study the band structure of phosphorene. From the locations of electronic bands, and band edges, we estimate the Fermi level and work function. This leads us to define a valid material specific parameter space and establish a formalism for estimating thermionic electron emission current from phosphorene. Finally we demonstrate how the emission current can be enhanced substantially under the effect of photon irradiation. We observe that photoemission flux to strongly dominate over its coexisting counterpart thermionic emission flux. Anisotropy in phosphorene structure plays important role in enhancing the flux. The approach which is valid over a much wider range of parameters is successfully tested against recently performed experiments in a different context. The results open up a new possibility for application of phosphorene based thermionic and photo-thermionic energy converters.
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Affiliation(s)
- S Madas
- ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, Szeged, 6720, Hungary
| | - S K Mishra
- ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, Szeged, 6720, Hungary
- Physical Research Laboratory (PRL), Navrangpura, Ahmedabad, 380009, India
| | - S Kahaly
- ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, Szeged, 6720, Hungary.
| | - M Upadhyay Kahaly
- ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, Szeged, 6720, Hungary.
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