1
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Nandi S, Cohen SZ, Singh D, Poplinger M, Nanikashvili P, Naveh D, Lewi T. Unveiling Local Optical Properties Using Nanoimaging Phase Mapping in High-Index Topological Insulator Bi 2Se 3 Resonant Nanostructures. NANO LETTERS 2023; 23:11501-11509. [PMID: 37890054 DOI: 10.1021/acs.nanolett.3c03128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Topological insulators are materials characterized by an insulating bulk and high mobility topologically protected surface states, making them promising candidates for future optoelectronic and quantum devices. Although their electronic properties have been extensively studied, their mid-infrared (MIR) properties and prospective photonic capabilities have not been fully uncovered. Here, we use a combination of far-field and near-field nanoscale imaging and spectroscopy to study chemical vapor deposition-grown Bi2Se3 nanobeams (NBs). We extract the MIR optical constants of Bi2Se3, revealing refractive index values as high as n ∼ 6.4, and demonstrate that the NBs support Mie resonances across the MIR. Local near-field reflection phase mapping reveals domains of various phase shifts, providing information on the local optical properties of the NBs. We experimentally measure up to 2π phase-shift across the resonance, in excellent agreement with finite-difference time-domain simulations. This work highlights the potential of Bi2Se3 for quantum circuitry, nonlinear generation, high-Q metaphotonics, and photodetection.
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Affiliation(s)
- Sukanta Nandi
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Shany Z Cohen
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Danveer Singh
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Michal Poplinger
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Pilkhaz Nanikashvili
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Doron Naveh
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Tomer Lewi
- Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
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2
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Nagaura T, Ashok A, Alowasheeir A, Vasanth A, Han M, Yamauchi Y. Mesoporous Semiconductive Bi 2Se 3 Films. NANO LETTERS 2023. [PMID: 37289968 DOI: 10.1021/acs.nanolett.3c00183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bi2Se3 is a semiconductive material possessing a bandgap of 0.3 eV, and its unique band structure has paved the way for diverse applications. Herein, we demonstrate a robust platform for synthesizing mesoporous Bi2Se3 films with uniform pore sizes via electrodeposition. Block copolymer micelles act as soft templates in the electrolyte to create a 3D porous nanoarchitecture. By controlling the length of the block copolymer, the pore size is adjusted to 9 and 17 nm precisely. The nonporous Bi2Se3 film exhibits a tunneling current in a vertical direction of 52.0 nA, but upon introducing porosity (9 nm pores), the tunneling current increases significantly to 684.6 nA, suggesting that the conductivity of Bi2Se3 films is dependent on the pore structure and surface area. The abundant porous architecture exposes a larger surface area of Bi2Se3 to the surrounding air within the same volume, thereby augmenting its metallic properties.
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Affiliation(s)
- Tomota Nagaura
- School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Aditya Ashok
- School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Azhar Alowasheeir
- Department of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Arya Vasanth
- Amrita School for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, Kerala 682041, India
| | - Minsu Han
- School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Yusuke Yamauchi
- School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia
- Department of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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3
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Souza PB, Tumelero MA, Faccio R, Ahmed R, Plá Cid CC, Zangari G, Pasa AA. Vibrational properties of metastable orthorhombic Bi 2Se 3. Phys Chem Chem Phys 2023; 25:14440-14448. [PMID: 37184536 DOI: 10.1039/d2cp04945g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Chalcogenide materials are being considered as some of the most promising systems for energy harvesting and energy conversion. Among them, the orthorhombic family of compounds X2Y3 (with X = Bi, Sb and Y = S, Se) has attracted special attention due to its interesting atomic structure and thermoelectric and optical properties. While Bi2S3 and Sb2Se3 have already been applied to solar cells, practical application of the new metastable Bi2Se3 is still a challenge due to the lack of data and knowledge on its properties. Here, the vibrational and structural properties of the orthorhombic metastable phase of Bi2Se3 are investigated by using Raman spectroscopy and ab initio calculations. We perform Raman spectroscopy measurements along with in situ thermal treatment on samples grown by electrochemical deposition. We show that by increasing the temperature an improved crystallization occurs in the orthorhombic structure, followed by recrystallization to the usual rhombohedral phase. Our results point out specific Raman modes of the orthorhombic phase. First principles computational results based on the density functional theory support the experimental data and describe three singlet Raman active vibrational modes, such as B(2)3g, B(2)2g and A(6)g.
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Affiliation(s)
- Paloma B Souza
- Departamento de Física, Universidade Federal de Santa Catarina, 88.040-900 Florianópolis, Brazil
| | - Milton A Tumelero
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, 91501-970 Porto Alegre, Brazil.
| | - Ricardo Faccio
- Centro NanoMat & Área Física, DETEMA, Facultad de Química, Universidad de la República (Udelar), Montevideo C.P. 11800, Uruguay
| | - Rasin Ahmed
- Department of Electrical Engineering, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Cristiani C Plá Cid
- Departamento de Física, Universidade Federal de Santa Catarina, 88.040-900 Florianópolis, Brazil
| | - Giovanni Zangari
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Andre A Pasa
- Departamento de Física, Universidade Federal de Santa Catarina, 88.040-900 Florianópolis, Brazil
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4
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Vijay V, Harish S, Archana J, Navaneethan M. Realization of an ultra-low lattice thermal conductivity in Bi 2Ag xSe 3 nanostructures for enhanced thermoelectric performance. J Colloid Interface Sci 2023; 637:340-353. [PMID: 36709591 DOI: 10.1016/j.jcis.2023.01.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 01/12/2023]
Abstract
Bismuth Selenide is a Tellurium free topological insulator in V-VI compounds with an excellent thermoelectric performance from room temperature to mid-temperature region. Herein, hydrothermally prepared polycrystalline Bi2AgxSe3 nanostructures have been reported for thermoelectric application. The crystal structure identification and morphology with the elemental presence were analyzed by XRD (X-ray diffraction), HR-SEM with EDS (High resolution scanning electron microscope with energy dispersive X-ray), and HR-TEM (High-resolution transmission electron microscope) measurements. The reduced lattice thermal conductivity and enhanced electrical transport properties synergistically boost the thermoelectric properties through the highly-dense stacking faults with the presence of dislocations. The IFFT (Inverse Fast Fourier Transform) pattern reveals the existence of stacking faults and dislocations. These highly dense stacking faults and dislocations act as active phonon scattering centers, which can contribute to effective phonon scattering resultsin extremely low lattice thermal conduction of 0.3 W/mK at 543 K. On the other hand, the involvement of phonon-phonon scattering primarily reduced the lattice thermal conductivity at elevated temperatures. In addition, phonon-carrier scattering was less compared to phonon-phonon scattering at elevated temperature region. Moreover, the enhancement of electrical conductivity and controlled reduction of the Seebeck coefficient plays a vital role in achieving the maximum power factor of 335 μW/mK2 at 543 K due to the energy filtering effect. The synergistic combination of low thermal conduction and the maximum power factor helps to achieve the high peak zT of 0.3 at 543 K.
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Affiliation(s)
- V Vijay
- Functional Materials and Energy Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, India
| | - S Harish
- Functional Materials and Energy Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, India; Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu, Shizuoka 432-8011, Japan
| | - J Archana
- Functional Materials and Energy Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, India
| | - M Navaneethan
- Functional Materials and Energy Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, India; Nanotechnology Research Center (NRC), Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603203, India.
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5
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Yu R, Cao JF, Meng XY, Zhu FY, Li JQ, Qu GX, Huang YB, Wang Y, Tai RZ. Highly Tunable Charge-Spin Conversion in Topological Insulator Cr 0.08-(Bi 0.37Sb 0.63) 1.92Te 3 via Ferroelectric Polarization. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48171-48178. [PMID: 36251523 DOI: 10.1021/acsami.2c09778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Topological insulators possess strong spin-orbit coupling, which potentially presents efficient charge-spin interconversion. The effective manipulation of this conversion plays a central role in spin-based device applications and is attracting increasing attention nowadays. In this study, by constructing a multifunctional hybrid device Cr-BST/Py/PMN-PT and applying spin-torque ferromagnetic resonance measurement, continuously controllable charge-spin conversion efficiency and even the enhancement of its value up to about 450% are realized via regulation of the ferroelectric polarization in the topological insulator Cr-BST. The band structure of Cr-BST characterized by angle-resolved photoelectron spectroscopy measurement presents an apparent Dirac-like state located at the large band gap of the bulk state near the Fermi level, which indicates a surface state-dominated contribution to the charge-spin conversion. Further investigation via density functional theory on the electronic structure of BST verifies that the controllable conversion efficiency dominantly originates from the evolution of the band structure under strain modulation. These findings demonstrate TIs as one of the promising materials for the charge-spin interconversion and its regulation, which are instructive for low-dissipation spintronics devices.
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Affiliation(s)
- Rui Yu
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Jie Feng Cao
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Xiang Yu Meng
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Fang Yuan Zhu
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Jun Qin Li
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Ge Xing Qu
- Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
| | - Yao Bo Huang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Yong Wang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
| | - Ren Zhong Tai
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, China
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6
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Salvato M, Crescenzi MD, Scagliotti M, Castrucci P, Boninelli S, Caruso GM, Liu Y, Mikkelsen A, Timm R, Nahas S, Black-Schaffer A, Kunakova G, Andzane J, Erts D, Bauch T, Lombardi F. Nanometric Moiré Stripes on the Surface of Bi 2Se 3 Topological Insulator. ACS NANO 2022; 16:13860-13868. [PMID: 36098662 PMCID: PMC9527797 DOI: 10.1021/acsnano.2c02515] [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: 03/13/2022] [Accepted: 09/07/2022] [Indexed: 06/15/2023]
Abstract
Mismatch between adjacent atomic layers in low-dimensional materials, generating moiré patterns, has recently emerged as a suitable method to tune electronic properties by inducing strong electron correlations and generating novel phenomena. Beyond graphene, van der Waals structures such as three-dimensional (3D) topological insulators (TIs) appear as ideal candidates for the study of these phenomena due to the weak coupling between layers. Here we discover and investigate the origin of 1D moiré stripes on the surface of Bi2Se3 TI thin films and nanobelts. Scanning tunneling microscopy and high-resolution transmission electron microscopy reveal a unidirectional strained top layer, in the range 14-25%, with respect to the relaxed bulk structure, which cannot be ascribed to the mismatch with the substrate lattice but rather to strain induced by a specific growth mechanism. The 1D stripes are characterized by a spatial modulation of the local density of states, which is strongly enhanced compared to the bulk system. Density functional theory calculations confirm the experimental findings, showing that the TI surface Dirac cone is preserved in the 1D moiré stripes, as expected from the topology, though with a heavily renormalized Fermi velocity that also changes between the top and valley of the stripes. The strongly enhanced density of surface states in the TI 1D moiré superstructure can be instrumental in promoting strong correlations in the topological surface states, which can be responsible for surface magnetism and topological superconductivity.
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Affiliation(s)
- Matteo Salvato
- Dipartimento
di Fisica and INFN, Università di
Roma “Tor Vergata”, 00133 Roma, Italy
| | - Maurizio De Crescenzi
- Dipartimento
di Fisica and INFN, Università di
Roma “Tor Vergata”, 00133 Roma, Italy
| | - Mattia Scagliotti
- Dipartimento
di Fisica and INFN, Università di
Roma “Tor Vergata”, 00133 Roma, Italy
| | - Paola Castrucci
- Dipartimento
di Fisica and INFN, Università di
Roma “Tor Vergata”, 00133 Roma, Italy
| | | | | | - Yi Liu
- Division
of Synchrotron Radiation Research, Department of Physics and NanoLund, Lund University, 221 00 Lund, Sweden
| | - Anders Mikkelsen
- Division
of Synchrotron Radiation Research, Department of Physics and NanoLund, Lund University, 221 00 Lund, Sweden
| | - Rainer Timm
- Division
of Synchrotron Radiation Research, Department of Physics and NanoLund, Lund University, 221 00 Lund, Sweden
| | - Suhas Nahas
- Department
of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Annica Black-Schaffer
- Department
of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Gunta Kunakova
- Institute
of Chemical Physics, University of Latvia, LV-1586 Riga, Latvia
- Quantum Device
Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Goteborg, Sweden
| | - Jana Andzane
- Institute
of Chemical Physics, University of Latvia, LV-1586 Riga, Latvia
| | - Donats Erts
- Institute
of Chemical Physics, University of Latvia, LV-1586 Riga, Latvia
| | - Thilo Bauch
- Quantum Device
Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Goteborg, Sweden
| | - Floriana Lombardi
- Quantum Device
Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Goteborg, Sweden
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7
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Chen M, de Oliveira TVAG, Ilyakov I, Nörenberg T, Kuschewski F, Deinert JC, Awari N, Ponomaryov A, Kuntzsch M, Kehr SC, Eng LM, Gensch M, Kovalev S. Terahertz-slicing - an all-optical synchronization for 4 th generation light sources. OPTICS EXPRESS 2022; 30:26955-26966. [PMID: 36236877 DOI: 10.1364/oe.454908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/01/2022] [Indexed: 06/16/2023]
Abstract
A conceptually new approach to synchronizing accelerator-based light sources and external laser systems is presented. The concept is based on utilizing a sufficiently intense accelerator-based single-cycle terahertz pulse to slice a thereby intrinsically synchronized femtosecond-level part of a longer picosecond laser pulse in an electro-optic crystal. A precise synchronization of the order of 10 fs is demonstrated, allowing for real-time lock-in amplifier signal demodulation. We demonstrate successful operation of the concept with three benchmark experiments using a 4th generation accelerator-based terahertz light source, i.e. (i) far-field terahertz time-domain spectroscopy, (ii) terahertz high harmonic generation spectroscopy, and (iii) terahertz scattering-type scanning near-field optical microscopy.
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8
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Nowak K, Jurczyszyn M, Chrobak M, Maćkosz K, Naumov A, Olszowska N, Rosmus M, Miotkowski I, Kozłowski A, Sikora M, Przybylski M. Influence of Doping on the Topological Surface States of Crystalline Bi2Se3 Topological Insulators. MATERIALS 2022; 15:ma15062083. [PMID: 35329534 PMCID: PMC8949243 DOI: 10.3390/ma15062083] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/01/2022] [Accepted: 03/04/2022] [Indexed: 02/04/2023]
Abstract
We present STM/STS, ARPES and magnetotransport studies of the surface topography and electronic structure of pristine Bi2Se3 in comparison to Bi1.96Mg0.04Se3 and Bi1.98Fe0.02Se3. The topography images reveal a large number of complex, triangle-shaped defects at the surface. The local electronic structure of both the defected and non-defected regions is examined by STS. The defect-related states shift together with the Dirac point observed in the undefected area, suggesting that the local electronic structure at the defects is influenced by doping in the same way as the electronic structure of the undefected surface. Additional information about the electronic structure of the samples is provided by ARPES, which reveals the dependence of the bulk and surface electronic bands on doping, including such parameters as the Fermi wave vector. The subtle changes of the surface electronic structure by doping are verified with magneto-transport measurements at low temperatures (200 mK) allowing the detection of Shubnikov-de Haas (SdH) quantum oscillations.
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Affiliation(s)
- Kamil Nowak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Michał Jurczyszyn
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
- Correspondence: ; Tel.: +48-12-617-5284
| | - Maciej Chrobak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Krzysztof Maćkosz
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Andrii Naumov
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Natalia Olszowska
- National Synchrotron Radiation Centre, Jagiellonian University, 30-392 Krakow, Poland; (N.O.); (M.R.)
| | - Marcin Rosmus
- National Synchrotron Radiation Centre, Jagiellonian University, 30-392 Krakow, Poland; (N.O.); (M.R.)
- Marian Smoluchowski Institute of Physics, Jagiellonian University, 30-348 Krakow, Poland
| | - Ireneusz Miotkowski
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA;
| | - Andrzej Kozłowski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
| | - Marcin Sikora
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Marek Przybylski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
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9
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Mapping propagation of collective modes in Bi 2Se 3 and Bi 2Te 2.2Se 0.8 topological insulators by near-field terahertz nanoscopy. Nat Commun 2021; 12:6672. [PMID: 34795216 PMCID: PMC8602307 DOI: 10.1038/s41467-021-26831-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/25/2021] [Indexed: 11/09/2022] Open
Abstract
Near-field microscopy discloses a peculiar potential to explore novel quantum state of matter at the nanoscale, providing an intriguing playground to investigate, locally, carrier dynamics or propagation of photoexcited modes as plasmons, phonons, plasmon-polaritons or phonon-polaritons. Here, we exploit a combination of hyperspectral time domain spectroscopy nano-imaging and detectorless scattering near-field optical microscopy, at multiple terahertz frequencies, to explore the rich physics of layered topological insulators as Bi2Se3 and Bi2Te2.2Se0.8, hyperbolic materials with topologically protected surface states. By mapping the near-field scattering signal from a set of thin flakes of Bi2Se3 and Bi2Te2.2Se0.8 of various thicknesses, we shed light on the nature of the collective modes dominating their optical response in the 2-3 THz range. We capture snapshots of the activation of transverse and longitudinal optical phonons and reveal the propagation of sub-diffractional hyperbolic phonon-polariton modes influenced by the Dirac plasmons arising from the topological surface states and of bulk plasmons, prospecting new research directions in plasmonics, tailored nanophotonics, spintronics and quantum technologies.
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10
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Xiong Y, Zhou G, Lai NC, Wang X, Lu YC, Prezhdo OV, Xu D. Chemically Switchable n-Type and p-Type Conduction in Bismuth Selenide Nanoribbons for Thermoelectric Energy Harvesting. ACS NANO 2021; 15:2791-2799. [PMID: 33556241 DOI: 10.1021/acsnano.0c08685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Realizing switchable n-type and p-type conduction in bismuth selenide (Bi2Se3), a traditional thermoelectric material and a topological insulator, is highly beneficial for the development of thermoelectric devices and also of great interest for spintronics and quantum computing. In this work, switching between n-type and p-type conduction in single Bi2Se3 nanoribbons is achieved by a reversible copper (Cu) intercalation method. Density functional theory calculations reveal that such a switchable behavior arises from the electronic band structure distortion caused by the high-concentration Cu intercalation and the Cu substitution for Bi sites in the host lattice. A proof-of-concept in-plane thermoelectric generator is fabricated with one pair of the pristine n-type and intercalated p-type Bi2Se3 nanoribbons on a microfabricated device, which gives rise to an open-circuit voltage of 4.8 mV and a maximum output power of 0.3 nW under a temperature difference of 29.2 K. This work demonstrates switchable n-type and p-type electrical conduction in Bi2Se3 nanoribbons via a facile chemical approach and the practical application of nanoribbons in a thermoelectric device.
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Affiliation(s)
- Yucheng Xiong
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Special Administrative Region China
| | - Guoqing Zhou
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
| | - Nien-Chu Lai
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Special Administrative Region China
| | - Xiaomeng Wang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Special Administrative Region China
| | - Yi-Chun Lu
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Special Administrative Region China
| | - Oleg V Prezhdo
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Dongyan Xu
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Special Administrative Region China
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11
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Pei K, Wang F, Han W, Yang S, Liu K, Liu K, Li H, Zhai T. Suppression of Persistent Photoconductivity of Rubrene Crystals using Gate-Tunable Rubrene/Bi 2 Se 3 Diodes with Photoinduced Negative Differential Resistance. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2002312. [PMID: 32627927 DOI: 10.1002/smll.202002312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/01/2020] [Indexed: 05/08/2023]
Abstract
Organic single-crystalline semiconductors show great potential in high-performance photodetectors. However, they suffer from persistent photoconductivity (PPC) due to the charge trapping, which has severely hindered high-speed imaging applications. Here, a universal strategy of solving the PPC by integrating with topological insulator Bi2 Se3 is provided. The rubrene/Bi2 Se3 heterojunctions are selected as an example for general demonstration due to the reproducibly high mobility and broad optoelectronic applications of rubrene crystals. By virtue of high carrier concentration on Bi2 Se3 surface and the strong built-in electrical field, the photoresponse of the heterotransistor is significantly reduced for more than two orders (from over 10 s to 54 ms), meanwhile the photoresponsivity can reach 124 A W-1 . To the best of knowledge, this operating speed is among the fastest responses in organic-inorganic heterojunctions. The heterotransistor also shows unique negative differential resistance under positive gate bias, which can be explained by photoinduced de-trapping of electron trap states in the bulk rubrene crystals. Besides, the rubrene/Bi2 Se3 heterojunction behaves as a gate-tunable backward-like diode due to the inhomogenous carrier distribution in the thick rubrene crystal and inversion of relative Fermi level positions. The findings demonstrate versatile functionalities of the rubrene/Bi2 Se3 heterojunctions for various emerging optoelectronic applications.
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Affiliation(s)
- Ke Pei
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Fakun Wang
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Wei Han
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Sanjun Yang
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Kailang Liu
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Kewei Liu
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, P. R. China
| | - Huiqiao Li
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, P. R. China
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Barton AT, Walsh LA, Smyth CM, Qin X, Addou R, Cormier C, Hurley PK, Wallace RM, Hinkle CL. Impact of Etch Processes on the Chemistry and Surface States of the Topological Insulator Bi 2Se 3. ACS APPLIED MATERIALS & INTERFACES 2019; 11:32144-32150. [PMID: 31416305 DOI: 10.1021/acsami.9b10625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The unique properties of topological insulators such as Bi2Se3 are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of Bi2Se3 have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He+ sputtering and inductively coupled plasma Cl2 and SF6 reactive etch chemistries on the physical, chemical, and electronic properties of Bi2Se3. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches Bi2Se3 but with residual Se-Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing Bi2Se3 nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF3 on the surface, prohibiting the use of SF6-based etching in Bi2Se3 processing.
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Affiliation(s)
- Adam T Barton
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Lee A Walsh
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
- Tyndall National Institute , University College Cork , Lee Maltings Complex , Cork T12R5CP , Ireland
| | - Christopher M Smyth
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Xiaoye Qin
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Rafik Addou
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Christopher Cormier
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Paul K Hurley
- Tyndall National Institute , University College Cork , Lee Maltings Complex , Cork T12R5CP , Ireland
| | - Robert M Wallace
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Christopher L Hinkle
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
- Department of Electrical Engineering , University of Notre Dame , Notre Dame , Indiana 46556 , United States
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Cermak P, Knotek P, Ruleova P, Holy V, Palka K, Kucek V, Benes L, Navratil J, Drasar C. High power factor and mobility of single crystals of Bi2Se3 induced by Mo doping. J SOLID STATE CHEM 2019. [DOI: 10.1016/j.jssc.2019.07.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Parbatani A, Song ES, Claypoole J, Yu B. High performance broadband bismuth telluride tetradymite topological insulator photodiode. NANOTECHNOLOGY 2019; 30:165201. [PMID: 30620938 DOI: 10.1088/1361-6528/aafc84] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
A small bulk gap and the presence of Dirac electrons due to conductive surface states make tetradymite topological insulators promising candidates for optoelectronic devices. In this work, we demonstrate a highly responsive Bi2Te3-Si heterostructure photodiode. The thermally evaporated Bi2Te3 film, exhibiting a nanocrystalline nature, shows p-type doping behavior due to bismuth vacancies. As a result of the work function difference between Bi2Te3 and p-type Si, charge transfer occurs and a Schottky barrier is formed. Using the thermionic emission model, the barrier height (ΦB) is extracted to be ∼0.405 eV. For minimizing the effect of extrinsic defects, the photodiodes were capped with graphene or Si3N4. Since graphene acts as an efficient photoexcited carrier collector, the graphene capped device outperforms the Si3N4 capped device. The higher quality Bi2Te3 nanocrystalline film of the Si3N4 capped photodiode contributes to a one-order-of-magnitude improvement in responsivity at 1550 nm wavelength, as compared to the graphene capped photodiode. The Si3N4 capped photodiode shows photoresponse even at zero bias for 1550 nm wavelength. Built-in potential due to charge transfer at the interface of Bi2Te3 and Si capped with a graphene electrode exhibits the highest responsivity (8.9 A W-1). Broadband photodetection is observed in both types of photodiodes.
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Affiliation(s)
- Asish Parbatani
- SUNY Polytechnic Institute, The State University of New York Albany, NY 12203, United States of America
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Growth, morphology and crystal structure of electrodeposited Bi2Se3 films: Influence of the substrate. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.01.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
This review briefly describes the development of synthetic topological insulator materials in the application of advanced electronic devices. As a new class of quantum matter, topological insulators with insulating bulk and conducting surface states have attracted attention in more and more research fields other than condensed matter physics due to their intrinsic physical properties, which provides an excellent basis for novel nanoelectronic, optoelectronic, and spintronic device applications. In comparison to the mechanically exfoliated samples, the newly emerging topological insulator nanostructures prepared with various synthetical approaches are more intriguing because the conduction contribution of the surface states can be significantly enhanced due to the larger surface-to-volume ratio, better manifesting the unique properties of the gapless surface states. So far, these synthetic topological insulator nanostructures have been implemented in different electrically accessible device platforms via electrical, magnetic and optical characterizations for material investigations and device applications, which will be introduced in this review.
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