1
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Kimberly TQ, Wang EYC, Navarro GD, Qi X, Ciesielski KM, Toberer ES, Kauzlarich SM. Into the Void: Single Nanopore in Colloidally Synthesized Bi 2Te 3 Nanoplates with Ultralow Lattice Thermal Conductivity. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2024; 36:6618-6626. [PMID: 39005532 PMCID: PMC11238327 DOI: 10.1021/acs.chemmater.4c01092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024]
Abstract
Bi2Te3 is a well-known thermoelectric material that was first investigated in the 1960s, optimized over decades, and is now one of the highest performing room-temperature thermoelectric materials to-date. Herein, we report on the colloidal synthesis, growth mechanism, and thermoelectric properties of Bi2Te3 nanoplates with a single nanopore in the center. Analysis of the reaction products during the colloidal synthesis reveals that the reaction progresses via a two-step nucleation and epitaxial growth: first of elemental Te nanorods and then the binary Bi2Te3 nanoplate growth. The rates of epitaxial growth can be controlled during the reaction, thus allowing the formation of a single nanopore in the center of the Bi2Te3 nanoplates. The size of the nanopore can be controlled by changing the pH of the reaction solution, where larger pores with diameter of ∼50 nm are formed at higher pH and smaller pores with diameter of ∼16 nm are formed at lower pH. We propose that the formation of the single nanopore is mediated by the Kirkendall effect and thus the reaction conditions allow for the selective control over pore size. Nanoplates have well-defined hexagonal facets as seen in the scanning and transmission electron microscopy images. The single nanopores have a thin amorphous layer at the edge, revealed by transmission electron microscopy. Thermoelectric properties of the pristine and single-nanopore Bi2Te3 nanoplates were measured in the parallel and perpendicular directions. These properties reveal strong anisotropy with a significant reduction to thermal conductivity and increased electrical resistivity in the perpendicular direction due to the higher number of nanoplate and nanopore interfaces. Furthermore, Bi2Te3 nanoplates with a single nanopore exhibit ultralow lattice thermal conductivity values, reaching ∼0.21 Wm-1K-1 in the perpendicular direction. The lattice thermal conductivity was found to be systematically lowered with pore size, allowing for the realization of a thermoelectric figure of merit, zT of 0.75 at 425 K for the largest pore size.
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Affiliation(s)
- Tanner Q Kimberly
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Evan Y C Wang
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Gustavo D Navarro
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Xiao Qi
- The Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Kamil M Ciesielski
- Department of Physics, Colorado School of Mines, 1523 Illinois Street, Golden, Colorado 80401, United States
| | - Eric S Toberer
- Department of Physics, Colorado School of Mines, 1523 Illinois Street, Golden, Colorado 80401, United States
| | - Susan M Kauzlarich
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
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2
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Rana N, Mukherjee S, Singha P, Das S, Bandyopadhyay S, Banerjee A. Tailoring thermoelectric performance of n-type Bi 2Te 3through defect engineering and conduction band convergence. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:365703. [PMID: 38815604 DOI: 10.1088/1361-648x/ad5245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 05/30/2024] [Indexed: 06/01/2024]
Abstract
Bi2Te3, an archetypical tetradymite, is recognised as a thermoelectric (TE) material of potential application around room temperature. However, large energy gap (ΔEc) between the light and heavy conduction bands results in inferior TE performance in pristine bulkn-type Bi2Te3. Herein, we propose enhancement in TE performance of pristinen-type Bi2Te3through purposefully manipulating defect profile and conduction band convergence mechanism. Twon-type Bi2Te3samples, S1 and S2, are prepared by melting method under different synthesis condition. The structural as well as microstructural evidence of the samples are obtained through powder x-ray diffraction and transmission electron microscopic study. Optothermal Raman spectroscopy is utilized for comprehensive study of temperature dependent phonon vibrational modes and total thermal conductivity (κ) of the samples which further validates the experimentally measured thermal conductivity. The Seebeck coefficient value is significantly increased from 235 μVK-1(sample S1) to 310 μVK-1(sample S2). This is further justified by conduction band convergence, where ΔEcis reduced from 0.10 eV to 0.05 eV, respectively. To verify the band convergence, the double band Pisarenko model is employed. Large power factor (PF) of 2190 μWm-1K-2and lowerκvalue leading toZTof 0.56 at 300 K is gained in S2. The obtainedPFandZTvalue are among the highest values reported for pristinen-type bulk Bi2Te3. In addition, appreciable value of TE quality factor and compatibility factor (2.7 V-1) at room temperature are also achieved, indicating the usefulness of the material in TE module.
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Affiliation(s)
- Nabakumar Rana
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
| | - Suchandra Mukherjee
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
| | - Pintu Singha
- School of Physics, Indian Institute of Science Education and Research, Maruthamala PO, Thiruvananthapuram, Kerala 695 551, India
| | - Subarna Das
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur PO, Bangalore 560064, India
| | - Sudipta Bandyopadhyay
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
- Center for Research in Nanoscience and Nanotechnology, University of Calcutta, JD-2, Sector-III, Saltlake, Kolkata 700 106, India
| | - Aritra Banerjee
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
- Center for Research in Nanoscience and Nanotechnology, University of Calcutta, JD-2, Sector-III, Saltlake, Kolkata 700 106, India
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3
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Wei XK, Jalil AR, Rüßmann P, Ando Y, Grützmacher D, Blügel S, Mayer J. Atomic Diffusion-Induced Polarization and Superconductivity in Topological Insulator-Based Heterostructures. ACS NANO 2024; 18:571-580. [PMID: 38126781 PMCID: PMC10786152 DOI: 10.1021/acsnano.3c08601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
The proximity effect at a highly transparent interface of an s-wave superconductor (S) and a topological insulator (TI) provides a promising platform to create Majorana zero modes in artificially designed heterostructures. However, structural and chemical issues pertinent to such interfaces have been poorly explored so far. Here, we report the discovery of Pd diffusion-induced polarization at interfaces between superconductive Pd1+x(Bi0.4Te0.6)2 (xPBT, 0 ≤ x ≤ 1) and Pd-intercalated Bi2Te3 by using atomic-resolution scanning transmission electron microscopy. Our quantitative image analysis reveals that nanoscale lattice strain and QL polarity synergistically suppress and promote Pd diffusion at the normal and parallel interfaces, formed between Te-Pd-Bi triple layers (TLs) and Te-Bi-Te-Bi-Te quintuple layers (QLs), respectively. Further, our first-principles calculations unveil that the superconductivity of the xPBT phase and topological nature of the Pd-intercalated Bi2Te3 phase are robust against the broken inversion symmetry. These findings point out the necessity of considering the coexistence of electric polarization with superconductivity and topology in such S-TI systems.
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Affiliation(s)
- Xian-Kui Wei
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Abdur Rehman Jalil
- Peter
Grünberg Institute and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Philipp Rüßmann
- Institute
for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany
- Peter
Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA, 52425 Jülich, Germany
| | - Yoichi Ando
- Physics
Institute II, University of Cologne, Zülpicher Straße 77, 50937 Köln, Germany
| | - Detlev Grützmacher
- Peter
Grünberg Institute and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Stefan Blügel
- Peter
Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA, 52425 Jülich, Germany
| | - Joachim Mayer
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Central
Facility for Electron Microscopy, RWTH Aachen
University, Ahornstraße
55, 52074 Aachen, Germany
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4
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Imam NG, Elyamny S, Aquilanti G, Pollastri S, Gigli L, Kashyout AEHB. Comprehensive study of nanostructured Bi 2Te 3 thermoelectric materials - insights from synchrotron radiation XRD, XAFS, and XRF techniques. RSC Adv 2024; 14:1875-1887. [PMID: 38192325 PMCID: PMC10772705 DOI: 10.1039/d3ra06731a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/21/2023] [Indexed: 01/10/2024] Open
Abstract
In this contribution, a comprehensive study of nanostructured Bi2Te3 (BT) thermoelectric material was performed using a combination of synchrotron radiation-based techniques such as XAFS, and XRF, along with some other laboratory techniques such as XRD, XPS, FESEM, and HRTEM. This study aims to track the change in morphological, compositional, average and local/electronic structures of Bi2Te3 of two different phases; nanostructure (thin film) and nanopowders (NPs). Bi2Te3 nanomaterial was fabricated as pellets using zone melting process in a one step process, while Bi2Te3 thin film was deposited on sodalime glass substrate using a vacuum thermal evaporation technique. Synchrotron radiation-based Bi LIII-edge fluorescence-mode X-ray absorption fine structure (XAFS) technique was performed to probe locally the electronic and fine structures of BT thin film around the Bi atom, while transmission-mode XAFS was used for BT NPs distributed in the PVP matrix. The structural features of the collected Bi LIII XANES spectra of thin film and powder samples of BT are compared with the simulated XANES spectrum of BT calculated using FDMNES code at 5 Å cluster size. Combining different off-line structural characterization techniques (XRD, FESEM, XPS, and HRTEM), along with those of synchrotron radiation-based techniques (XAFS and XRF) is necessary for complementary and supported average crystal, chemical, morphological and local electronic structural analyses for unveiling the variation between Bi2Te3 in the nanostructure/thin film and nanopowder morphology, and then connecting between the structural features and functions of BT in two different morphologies. After that, we measured the Seebeck coefficient and the power factor values for both the BT nanopowder and thin film.
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Affiliation(s)
- N G Imam
- Experimental Nuclear Physics Department (Solid State Laboratory), Nuclear Research Center (NRC), Egyptian Atomic Energy Authority (EAEA) Cairo 13759 Egypt
- Elettra - Sincrotrone Trieste Strada Statale 14 - km 163,5 in AREA Science Park, Basovizza 34149 Trieste Italy
| | - Shaimaa Elyamny
- Electronic Materials Research Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA-City) New Borg El-Arab City, P.O. Box 21934 Alexandria Egypt
| | - Giuliana Aquilanti
- Elettra - Sincrotrone Trieste Strada Statale 14 - km 163,5 in AREA Science Park, Basovizza 34149 Trieste Italy
| | - Simone Pollastri
- Elettra - Sincrotrone Trieste Strada Statale 14 - km 163,5 in AREA Science Park, Basovizza 34149 Trieste Italy
| | - Lara Gigli
- Elettra - Sincrotrone Trieste Strada Statale 14 - km 163,5 in AREA Science Park, Basovizza 34149 Trieste Italy
| | - Abd El-Hady B Kashyout
- Electronic Materials Research Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA-City) New Borg El-Arab City, P.O. Box 21934 Alexandria Egypt
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5
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Park JK, Kang DH, Park SK, Lee JS. NMR probe of suppressed bulk conductivity in the topological insulator Bi0.5Sb1.5Te3. RSC Adv 2022; 12:2531-2535. [PMID: 35425320 PMCID: PMC8979140 DOI: 10.1039/d1ra07194g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 01/06/2022] [Indexed: 11/21/2022] Open
Abstract
We investigated insulating behaviors in the bulk of the topological insulator Bi0.5Sb1.5Te3 varying in particle size using 125Te NMR spectroscopy, within the framework of a theoretical relaxation model of the Dirac electron system.
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Affiliation(s)
- Jun Kue Park
- Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju 38180, Korea
| | - Do Hoon Kang
- Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju 38180, Korea
| | - Sung Kyun Park
- Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju 38180, Korea
| | - Jae Sang Lee
- Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongju 38180, Korea
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6
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Su SH, Chang JT, Chuang PY, Tsai MC, Peng YW, Lee MK, Cheng CM, Huang JCA. Epitaxial Growth and Structural Characterizations of MnBi 2Te 4 Thin Films in Nanoscale. NANOMATERIALS 2021; 11:nano11123322. [PMID: 34947669 PMCID: PMC8703544 DOI: 10.3390/nano11123322] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 11/30/2022]
Abstract
The intrinsic magnetic topological insulator MnBi2Te4 has attracted much attention due to its special magnetic and topological properties. To date, most reports have focused on bulk or flake samples. For material integration and device applications, the epitaxial growth of MnBi2Te4 film in nanoscale is more important but challenging. Here, we report the growth of self-regulated MnBi2Te4 films by the molecular beam epitaxy. By tuning the substrate temperature to the optimal temperature for the growth surface, the stoichiometry of MnBi2Te4 becomes sensitive to the Mn/Bi flux ratio. Excessive and deficient Mn resulted in the formation of a MnTe and Bi2Te3 phase, respectively. The magnetic measurement of the 7 SL MnBi2Te4 film probed by the superconducting quantum interference device (SQUID) shows that the antiferromagnetic order occurring at the Néel temperature 22 K is accompanied by an anomalous magnetic hysteresis loop along the c-axis. The band structure measured by angle-resolved photoemission spectroscopy (ARPES) at 80 K reveals a Dirac-like surface state, which indicates that MnBi2Te4 has topological insulator properties in the paramagnetic phase. Our work demonstrates the key growth parameters for the design and optimization of the synthesis of nanoscale MnBi2Te4 films, which are of great significance for fundamental research and device applications involving antiferromagnetic topological insulators.
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Affiliation(s)
- Shu-Hsuan Su
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Jen-Te Chang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Pei-Yu Chuang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Ming-Chieh Tsai
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Yu-Wei Peng
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Min Kai Lee
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
- Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106335, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
- Correspondence: (C.-M.C.); (J.-C.A.H.)
| | - Jung-Chung Andrew Huang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
- Department of Applied Physics, National University of Kaohsiung, Kaohsiung, 811, Taiwan
- Correspondence: (C.-M.C.); (J.-C.A.H.)
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7
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Osca J, Moors K, Sorée B, Serra L. Fabry-Pérot interferometry with gate-tunable 3D topological insulator nanowires. NANOTECHNOLOGY 2021; 32:435002. [PMID: 34284353 DOI: 10.1088/1361-6528/ac1633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
Three-dimensional topological insulator (3D TI) nanowires display remarkable magnetotransport properties that can be attributed to their spin-momentum-locked surface states such as quasiballistic transport and Aharonov-Bohm oscillations. Here, we focus on the transport properties of a 3D TI nanowire with a gated section that forms an electronic Fabry-Pérot (FP) interferometer that can be tuned to act as a surface-state filter or energy barrier. By tuning the carrier density and length of the gated section of the wire, the interference pattern can be controlled and the nanowire can become fully transparent for certain topological surface-state input modes while completely filtering out others. We also consider the interplay of FP interference with an external magnetic field, with which Klein tunneling can be induced, and transverse asymmetry of the gated section, e.g. due to a top-gated structure, which displays an interesting analogy with Rashba nanowires. Due to its rich conductance phenomenology, we propose a 3D TI nanowire with gated section as an ideal setup for a detailed transport-based characterization of 3D TI nanowire surface states near the Dirac point, which could be useful towards realizing 3D TI nanowire-based topological superconductivity and Majorana bound states.
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Affiliation(s)
- Javier Osca
- IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
- KU Leuven, ESAT-MICAS, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Kristof Moors
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Bart Sorée
- IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
- KU Leuven, ESAT-MICAS, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
- Universiteit Antwerpen, Departement Fysica, B-2020 Antwerpen, Belgium
| | - Llorenç Serra
- Institute of Interdisciplinary Physics and Complex Systems IFISC (CSIC-UIB), Palma, E-07122, Spain
- Department of Physics, University of the Balearic Islands, Palma, E-07122, Spain
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8
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Zhang M, Liu W, Zhang C, Xie S, Li Z, Hua F, Luo J, Wang Z, Wang W, Yan F, Cao Y, Liu Y, Wang Z, Uher C, Tang X. Identifying the Manipulation of Individual Atomic-Scale Defects for Boosting Thermoelectric Performances in Artificially Controlled Bi 2Te 3 Films. ACS NANO 2021; 15:5706-5714. [PMID: 33683108 DOI: 10.1021/acsnano.1c01039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The manipulation of individual intrinsic point defects is crucial for boosting the thermoelectric performances of n-Bi2Te3-based thermoelectric films, but was not achieved in previous studies. In this work, we realize the independent manipulation of Te vacancies VTe and antisite defects of TeBi and BiTe in molecular beam epitaxially grown n-Bi2Te3 films, which is directly monitored by a scanning tunneling microscope. By virtue of introducing dominant TeBi antisites, the n-Bi2Te3 film can achieve the state-of-the-art thermoelectric power factor of 5.05 mW m-1 K-2, significantly superior to films containing VTe and BiTe as dominant defects. Angle-resolved photoemission spectroscopy and systematic transport studies have revealed two detrimental effects regarding VTe and BiTe, which have not been discovered before: (1) The presence of BiTe antisites leads to a reduction of the carrier effective mass in the conduction band; and (2) the intrinsic transformation of VTe to BiTe during the film growth results in a built-in electric field along the film thickness direction and thus is not beneficial for the carrier mobility. This research is instructive for further engineering defects and optimizing electronic transport properties of n-Bi2Te3 and other technologically important thermoelectric materials.
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Affiliation(s)
- Min Zhang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Wei Liu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Cheng Zhang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Sen Xie
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Zhi Li
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Fuqiang Hua
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Jiangfan Luo
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhaohui Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Wei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Fan Yan
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Yu Cao
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Yong Liu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
- The Key Laboratory of Artificial Micro/Nano Structures of Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Ziyu Wang
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Ctirad Uher
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
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9
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Hatta S, Obayashi K, Okuyama H, Aruga T. Metallic conduction through van der Waals interfaces in ultrathin [Formula: see text] films. Sci Rep 2021; 11:5742. [PMID: 33707477 PMCID: PMC7952583 DOI: 10.1038/s41598-021-85078-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 02/24/2021] [Indexed: 11/18/2022] Open
Abstract
While the van der Waals (vdW) interface in layered materials hinders the transport of charge carriers in the vertical direction, it serves a good horizontal conduction path. We have investigated electrical conduction of few quintuple-layer (QL) [Formula: see text] films by in situ four-point probe conductivity measurement. The impact of the vdW (Te-Te) interface appeared as a large conductivity increase with increasing thickness from 1 to 2 QL. Angle-resolved photoelectron spectroscopy and first-principles calculations reveal the confinement of bulk-like conduction band (CB) state into the vdW interface. Our analysis based on the Boltzmann equation showed that the conduction of the CB has a long mean free path compared to the surface-state conduction. This is mainly attributed to the spatial separation of the CB electrons and the donor defects located at the Bi sites.
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Affiliation(s)
- Shinichiro Hatta
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - Ko Obayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - Hiroshi Okuyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - Tetsuya Aruga
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
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10
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Lukyanova LN, Makarenko IV, Usov OA. STM and STS studies of topological n-type (Bi, In) 2(Te, Se, S) 3thermoelectrics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:465701. [PMID: 32702688 DOI: 10.1088/1361-648x/aba8c8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
In topological n-type thermoelectrics based on Bi2Te3with atomic substitutions Bi → In, Te → Se, S, the morphology and the surface states of Dirac fermions on the interlayer (0001) surface of van der Waals were studied by scanning tunneling microscopy and spectroscopy (STM/STS) techniques. By the STM method, the dark and light spots on the surface were found, which intensities depend on the composition and thermoelectric properties of solid solutions such as the Seebeck coefficient and thermoelectric power factor. The observed surface morphology features in the solid solutions are explained by distortions of surface electronic states originated from atomic substitutions, the influence of doping impurity, and formation mainly of substitutional impurity defects in thermoelectrics. The dips associated with substitutional impurities and antisite defects were found from the analysis of the height profiles obtained on the (0001) surface. Fast Fourier transform of the morphology STM images of the (0001) surface were used to obtain the interference patterns of the quasiparticles excitation caused by surface electrons scattering by defects. The Dirac point energy and its fluctuations, peak energies of surface defects, the positions of the valence and conduction band edges, and the energy gap were determined from an analysis of tunneling spectra. A correlation between the parameters of surface states of Dirac fermions and thermoelectric properties was found. Thus, a contribution of the fermions surface states increases with rise of the surface concentration in solid solutions with high power factor, and the largest concentration value was observed in the Bi1.98In0.02Te2.85Se0.15composition. The dependences of Fermi energy on the wave vector for different solid solutions are described by a set of Dirac cone sections located within the limits of the fluctuations of the Dirac point energy that explained by weak changes of the Fermi velocity for studied atomic substitutions in sublattices of bismuth telluride.
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Affiliation(s)
- L N Lukyanova
- Ioffe Institute, Russian Academy of Sciences, St Petersburg 194021, Russia
| | - I V Makarenko
- Ioffe Institute, Russian Academy of Sciences, St Petersburg 194021, Russia
| | - O A Usov
- Ioffe Institute, Russian Academy of Sciences, St Petersburg 194021, Russia
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Kumar D, Lakhani A. Effect of band bending on topological surface transport of Bi 2Te 3 single crystal. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:115703. [PMID: 33316791 DOI: 10.1088/1361-648x/abd335] [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
Understanding the effect of surface to bulk coupling on topological surface states is important for harnessing the topological insulators for low dissipation electronics and quantum technologies. Here we investigate this effect on a low bulk carrier density Bi2Te3 single crystal using magnetoresistance, Hall resistivity, and Shubnikov-de Haas oscillations. Our results show the presence of high mobility surface bands and low mobility bulk bands. The surface states exhibit ambipolar transport without any gating. The mobility of surface states strongly depend on the nature of band bending, the upward band bending with holes as surface charge carrier exhibit large mobility while the downward band bending with electrons as surface charge carriers exhibit low surface mobility. The large mobility of surface Dirac holes is related to low surface defect density and small cyclotron mass. We also observe large magnetoresistance ∼285% due to multichannel quantum coherent transport in the bulk.
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Affiliation(s)
- Devendra Kumar
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India
| | - Archana Lakhani
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India
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12
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Qu Q, Liu B, Liang J, Li H, Wang J, Pan D, Sou IK. Expediting Hydrogen Evolution through Topological Surface States on Bi2Te3. ACS Catal 2020. [DOI: 10.1021/acscatal.9b04318] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Qing Qu
- Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Bin Liu
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jing Liang
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Hui Li
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jiannong Wang
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Ding Pan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Hong KongChina
| | - Iam Keong Sou
- Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
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