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Sui F, Li H, Qi R, Jin M, Lv Z, Wu M, Liu X, Zheng Y, Liu B, Ge R, Wu YN, Huang R, Yue F, Chu J, Duan C. Atomic-level polarization reversal in sliding ferroelectric semiconductors. Nat Commun 2024; 15:3799. [PMID: 38714769 PMCID: PMC11076638 DOI: 10.1038/s41467-024-48218-z] [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: 01/10/2024] [Accepted: 04/24/2024] [Indexed: 05/10/2024] Open
Abstract
Intriguing "slidetronics" has been reported in van der Waals (vdW) layered non-centrosymmetric materials and newly-emerging artificially-tuned twisted moiré superlattices, but correlative experiments that spatially track the interlayer sliding dynamics at atomic-level remain elusive. Here, we address the decisive challenge to in-situ trace the atomic-level interlayer sliding and the induced polarization reversal in vdW-layered yttrium-doped γ-InSe, step by step and atom by atom. We directly observe the real-time interlayer sliding by a 1/3-unit cell along the armchair direction, corresponding to vertical polarization reversal. The sliding driven only by low energetic electron-beam illumination suggests rather low switching barriers. Additionally, we propose a new sliding mechanism that supports the observed reversal pathway, i.e., two bilayer units slide towards each other simultaneously. Our insights into the polarization reversal via the atomic-scale interlayer sliding provide a momentous initial progress for the ongoing and future research on sliding ferroelectrics towards non-volatile storages or ferroelectric field-effect transistors.
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Affiliation(s)
- Fengrui Sui
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Haoyang Li
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Ruijuan Qi
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China.
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.
| | - Min Jin
- College of Materials, Shanghai Dianji University, Shanghai, 201306, China.
| | - Zhiwei Lv
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Menghao Wu
- School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xuechao Liu
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Yufan Zheng
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Beituo Liu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Rui Ge
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Yu-Ning Wu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China.
| | - Rong Huang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Fangyu Yue
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai, 200062, China.
| | - Junhao Chu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
- National Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Shanghai, 200083, China
| | - Chungang Duan
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, China
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai, 200062, China
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2
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Sprincean V, Qiu H, Tjardts T, Lupan O, Untilă D, Aktas C, Adelung R, Leontie L, Carlescu A, Gurlui S, Caraman M. Composition and Surface Optical Properties of GaSe:Eu Crystals before and after Heat Treatment. MATERIALS (BASEL, SWITZERLAND) 2024; 17:405. [PMID: 38255573 PMCID: PMC10817291 DOI: 10.3390/ma17020405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024]
Abstract
This work studies the technological preparation conditions, morphology, structural characteristics and elemental composition, and optical and photoluminescent properties of GaSe single crystals and Eu-doped β-Ga2O3 nanoformations on ε-GaSe:Eu single crystal substrate, obtained by heat treatment at 750-900 °C, with a duration from 30 min to 12 h, in water vapor-enriched atmosphere, of GaSe plates doped with 0.02-3.00 at. % Eu. The defects on the (0001) surface of GaSe:Eu plates serve as nucleation centers of β-Ga2O3:Eu crystallites. For 0.02 at. % Eu doping, the fundamental absorption edge of GaSe:Eu crystals at room temperature is formed by n = 1 direct excitons, while at 3.00 at. % doping, Eu completely shields the electron-hole bonds. The band gap of nanostructured β-Ga2O3:Eu layer, determined from diffuse reflectance spectra, depends on the dopant concentration and ranges from 4.64 eV to 4.87 eV, for 3.00 and 0.05 at. % doping, respectively. At 0.02 at. % doping level, the PL spectrum of ε-GaSe:Eu single crystals consists of the n = 1 exciton band, together with the impurity band with a maximum intensity at 800 nm. Fabry-Perrot cavities with a width of 9.3 μm are formed in these single crystals, which determine the interference structure of the impurity PL band. At 1.00-3.00 at. % Eu concentrations, the PL spectra of GaSe:Eu single crystals and β-Ga2O3:Eu nanowire/nanolamellae layers are determined by electronic transitions of Eu2+ and Eu3+ ions.
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Affiliation(s)
- Veaceslav Sprincean
- Faculty of Physics and Engineering, Moldova State University, 60 Alexei Mateevici Str., MD-2009 Chisinau, Moldova; (V.S.); (D.U.); (M.C.)
| | - Haoyi Qiu
- Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (H.Q.); (R.A.)
| | - Tim Tjardts
- Multicomponent Materials, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (T.T.); (C.A.)
| | - Oleg Lupan
- Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (H.Q.); (R.A.)
- Multicomponent Materials, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (T.T.); (C.A.)
- Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168, Stefan cel Mare Av., MD-2004 Chisinau, Moldova
- Department of Physics, University of Central Florida, Orlando, FL 32816-2385, USA
| | - Dumitru Untilă
- Faculty of Physics and Engineering, Moldova State University, 60 Alexei Mateevici Str., MD-2009 Chisinau, Moldova; (V.S.); (D.U.); (M.C.)
| | - Cenk Aktas
- Multicomponent Materials, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (T.T.); (C.A.)
| | - Rainer Adelung
- Functional Nanomaterials, Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstr. 2, D-24143 Kiel, Germany; (H.Q.); (R.A.)
| | - Liviu Leontie
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I, 700506 Iasi, Romania; (L.L.); (S.G.)
| | - Aurelian Carlescu
- Science Research Department, Institute of Interdisciplinary Research, Research Center in Environmental Sciences for the North-Eastern Romanian Region (CERNESIM), Alexandru Ioan Cuza University of Iasi, 11 Carol I, 700506 Iasi, Romania
| | - Silviu Gurlui
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I, 700506 Iasi, Romania; (L.L.); (S.G.)
| | - Mihail Caraman
- Faculty of Physics and Engineering, Moldova State University, 60 Alexei Mateevici Str., MD-2009 Chisinau, Moldova; (V.S.); (D.U.); (M.C.)
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3
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Luo W, Lawrie BJ, Puretzky AA, Tan Q, Gao H, Lingerfelt DB, Eichman G, Mcgee E, Swan AK, Liang L, Ling X. Imaging Strain-Localized Single-Photon Emitters in Layered GaSe below the Diffraction Limit. ACS NANO 2023. [PMID: 38044592 DOI: 10.1021/acsnano.3c05250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Nanoscale strain control of exciton funneling is an increasingly critical tool for the scalable production of single photon emitters (SPEs) in two-dimensional materials. However, conventional far-field optical microscopies remain constrained in spatial resolution by the diffraction limit and thus can provide only a limited description of nanoscale strain localization of SPEs. Here, we quantify the effects of nanoscale heterogeneous strain on the energy and brightness of GaSe SPEs on nanopillars with correlative cathodoluminescence, photoluminescence, and atomic force microscopy, supported by density functional theory simulations. We report the strain-localized SPEs have a broad range of emission wavelengths from 620 to 900 nm. We reveal substantial strain-controlled SPE wavelength tunability over a ∼100 nm spectral range and 2 orders of magnitude enhancement in the SPE brightness at the pillar center due to Type-I exciton funneling. In addition, we show that radiative biexciton cascade processes contribute to observed CL photon superbunching. Also, the GaSe SPEs show excellent stability, where their properties remain unchanged after electron beam exposure. We anticipate that this comprehensive study on the nanoscale strain control of two-dimensional SPEs will provide key insights to guide the development of truly deterministic quantum photonics.
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Affiliation(s)
- Weijun Luo
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Benjamin J Lawrie
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Qishuo Tan
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Hongze Gao
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - David B Lingerfelt
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gage Eichman
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Edward Mcgee
- Department of Electrical Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Anna K Swan
- Department of Electrical Engineering, Boston University, Boston, Massachusetts 02215, United States
- The Photonics Center, Boston University, Boston, Massachusetts 02215, United States
| | - Liangbo Liang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xi Ling
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
- The Photonics Center, Boston University, Boston, Massachusetts 02215, United States
- Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, United States
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4
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Qu J, Elgendy A, Cai R, Buckingham MA, Papaderakis AA, de Latour H, Hazeldine K, Whitehead GFS, Alam F, Smith CT, Binks DJ, Walton A, Skelton JM, Dryfe RAW, Haigh SJ, Lewis DJ. A Low-Temperature Synthetic Route Toward a High-Entropy 2D Hexernary Transition Metal Dichalcogenide for Hydrogen Evolution Electrocatalysis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2204488. [PMID: 36951493 DOI: 10.1002/advs.202204488] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 02/09/2023] [Indexed: 05/18/2023]
Abstract
High-entropy (HE) metal chalcogenides are a class of materials that have great potential in applications such as thermoelectrics and electrocatalysis. Layered 2D transition-metal dichalcogenides (TMDCs) are a sub-class of high entropy metal chalcogenides that have received little attention to date as their preparation currently involves complicated, energy-intensive, or hazardous synthetic steps. To address this, a low-temperature (500 °C) and rapid (1 h) single source precursor approach is successfully adopted to synthesize the hexernary high-entropy metal disulfide (MoWReMnCr)S2 . (MoWReMnCr)S2 powders are characterized by powder X-ray diffraction (pXRD) and Raman spectroscopy, which confirmed that the material is comprised predominantly of a hexagonal phase. The surface oxidation states and elemental compositions are studied by X-ray photoelectron spectroscopy (XPS) whilst the bulk morphology and elemental stoichiometry with spatial distribution is determined by scanning electron microscopy (SEM) with elemental mapping information acquired from energy-dispersive X-ray (EDX) spectroscopy. The bulk, layered material is subsequently exfoliated to ultra-thin, several-layer 2D nanosheets by liquid-phase exfoliation (LPE). The resulting few-layer HE (MoWReMnCr)S2 nanosheets are found to contain a homogeneous elemental distribution of metals at the nanoscale by high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) with EDX mapping. Finally, (MoWReMnCr)S2 is demonstrated as a hydrogen evolution electrocatalyst and compared to 2H-MoS2 synthesized using the molecular precursor approach. (MoWReMnCr)S2 with 20% w/w of high-conductivity carbon black displays a low overpotential of 229 mV in 0.5 M H2 SO4 to reach a current density of 10 mA cm-2 , which is much lower than the overpotential of 362 mV for MoS2 . From density functional theory calculations, it is hypothesised that the enhanced catalytic activity is due to activation of the basal plane upon incorporation of other elements into the 2H-MoS2 structure, in particular, the first row TMs Cr and Mn.
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Affiliation(s)
- Jie Qu
- Department of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Amr Elgendy
- Department of Chemistry and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Rongsheng Cai
- Department of Materials, National Graphene Institute and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Mark A Buckingham
- Department of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Athanasios A Papaderakis
- Department of Chemistry and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Hugo de Latour
- Department of Materials, National Graphene Institute and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Kerry Hazeldine
- Department of Chemistry and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - George F S Whitehead
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Firoz Alam
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Charles T Smith
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - David J Binks
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Alex Walton
- Department of Chemistry and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jonathan M Skelton
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Robert A W Dryfe
- Department of Chemistry and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Sarah J Haigh
- Department of Materials, National Graphene Institute and Sir Henry Royce Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - David J Lewis
- Department of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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5
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Wang W, Sun R, Shen W, Jia Z, Deepak FL, Zhang Y, Wang Z. Atomic structure and large magnetic anisotropy in air-sensitive layered ferromagnetic VI 3. NANOSCALE 2023; 15:4628-4635. [PMID: 36779225 DOI: 10.1039/d2nr06531b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We report the air-sensitivity, atomic structure, and magnetic anisotropy of VI3 single crystals. We find that VI3 nanocrystals exhibit a large MR/MS ratio of around 0.75 and a uniaxial anisotropic constant of an order of 105 erg cc-1 below the Curie temperature. Furthermore, density functional theory calculations reveal that both the monolayer and bulk VI3 are ferromagnetic insulators, and the magnetic moment of the system arises mainly from the d orbital of the V atom. These findings open a feasible avenue to fabricating TEM specimens of air-sensitive layered materials, providing an in-depth comprehensive understanding of a layered ferromagnetic VI3.
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Affiliation(s)
- Wenjie Wang
- College of Science, China Agricultural University, Beijing, 100083, China
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
| | - Rong Sun
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
- Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Cadiz, 11003, Spain.
| | - Wei Shen
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
- The Institute of Technological Sciences, Wuhan University, Wuhan, 430074, China
| | - Zhiyan Jia
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
- Institute of Quantum Materials and Devices, School of Materials Science and Engineering, Tiangong University, Tianjin, 300387, China
| | - Francis Leonard Deepak
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
| | - Yujie Zhang
- College of Science, Tianjin University of Technology, Tianjin, 300384, China.
| | - Zhongchang Wang
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, Braga, 4715-330, Portugal.
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6
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Yang B, Gao W, Li H, Gao P, Yang M, Pan Y, Wang C, Yang Y, Huo N, Zheng Z, Li J. Visible and infrared photodiode based on γ-InSe/Ge van der Waals heterojunction for polarized detection and imaging. NANOSCALE 2023; 15:3520-3531. [PMID: 36723020 DOI: 10.1039/d2nr06642d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Broadband photodetectors are a category of optoelectronic devices that have important applications in modern communication information. γ-InSe is a newly developed two-dimensional (2D) layered semiconductor with an air-stable and low-symmetry crystal structure that is suitable for polarization-sensitive photodetection. Herein, we report a P-N photodiode based on 3D Ge/2D γ-InSe van der Waals heterojunction (vdWH). A built-in electric field is introduced at the p-Ge/n-InSe interface to suppress the dark current and accelerate the separation of photogenerated carriers. Moreover, the heterojunction belongs to the accumulation mode with a well-designed type-II band arrangement, which is suitable for the fast separation of photogenerated carriers. Driven by these advantages, the device exhibits excellent photovoltaic performance within the detection range of 400 to 1600 nm and shows a double photocurrent peak at around 405 and 1550 nm. In particular, the responsivity (R) is up to 9.78 A W-1 and the specific detectivity (D*) reaches 5.38 × 1011 Jones with a fast response speed of 46/32 μs under a 1550 nm laser. Under blackbody radiation, the room temperature R and D* in the mid-wavelength infrared region are 0.203 A W-1 and 5.6 × 108 Jones, respectively. Moreover, polarization-sensitive light detection from 405-1550 nm was achieved, with the dichroism ratios of 1.44, 3.01, 1.71, 1.41 and 1.34 at 405, 635, 808, 1310 and 1550 nm, respectively. In addition, high-resolution single-pixel imaging capability is demonstrated at visible and near-infrared wavelengths. This work reveals the great potential of the γ-InSe/Ge photodiode for high-performance, broadband, air-stable and polarization-sensitive photodetection.
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Affiliation(s)
- Baoxiang Yang
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Wei Gao
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Hengyi Li
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Peng Gao
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Mengmeng Yang
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Yuan Pan
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Chuanglei Wang
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Yani Yang
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Nengjie Huo
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
| | - Zhaoqiang Zheng
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, P. R. China.
| | - Jingbo Li
- School of Semiconductor Science and Technology, Guangdong Provincial Key Laboratory of Chip and Integration Technology, South China Normal University, Guangzhou 528225, P. R. China.
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7
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Sliding ferroelectricity in van der Waals layered γ-InSe semiconductor. Nat Commun 2023; 14:36. [PMID: 36596789 PMCID: PMC9810696 DOI: 10.1038/s41467-022-35490-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 12/06/2022] [Indexed: 01/05/2023] Open
Abstract
Two-dimensional (2D) van-der-Waals (vdW) layered ferroelectric semiconductors are highly desired for in-memory computing and ferroelectric photovoltaics or detectors. Beneficial from the weak interlayer vdW-force, controlling the structure by interlayer twist/translation or doping is an effective strategy to manipulate the fundamental properties of 2D-vdW semiconductors, which has contributed to the newly-emerging sliding ferroelectricity. Here, we report unconventional room-temperature ferroelectricity, both out-of-plane and in-plane, in vdW-layered γ-InSe semiconductor triggered by yttrium-doping (InSe:Y). We determine an effective piezoelectric constant of ∼7.5 pm/V for InSe:Y flakes with thickness of ∼50 nm, about one order of magnitude larger than earlier reports. We directly visualize the enhanced sliding switchable polarization originating from the fantastic microstructure modifications including the stacking-faults elimination and a subtle rhombohedral distortion due to the intralayer compression and continuous interlayer pre-sliding. Our investigations provide new freedom degrees of structure manipulation for intrinsic properties in 2D-vdW-layered semiconductors to expand ferroelectric candidates for next-generation nanoelectronics.
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8
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Tracking single adatoms in liquid in a transmission electron microscope. Nature 2022; 609:942-947. [PMID: 35896149 DOI: 10.1038/s41586-022-05130-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 07/20/2022] [Indexed: 02/01/2023]
Abstract
Single atoms or ions on surfaces affect processes from nucleation1 to electrochemical reactions2 and heterogeneous catalysis3. Transmission electron microscopy is a leading approach for visualizing single atoms on a variety of substrates4,5. It conventionally requires high vacuum conditions, but has been developed for in situ imaging in liquid and gaseous environments6,7 with a combined spatial and temporal resolution that is unmatched by any other method-notwithstanding concerns about electron-beam effects on samples. When imaging in liquid using commercial technologies, electron scattering in the windows enclosing the sample and in the liquid generally limits the achievable resolution to a few nanometres6,8,9. Graphene liquid cells, on the other hand, have enabled atomic-resolution imaging of metal nanoparticles in liquids10. Here we show that a double graphene liquid cell, consisting of a central molybdenum disulfide monolayer separated by hexagonal boron nitride spacers from the two enclosing graphene windows, makes it possible to monitor, with atomic resolution, the dynamics of platinum adatoms on the monolayer in an aqueous salt solution. By imaging more than 70,000 single adatom adsorption sites, we compare the site preference and dynamic motion of the adatoms in both a fully hydrated and a vacuum state. We find a modified adsorption site distribution and higher diffusivities for the adatoms in the liquid phase compared with those in vacuum. This approach paves the way for in situ liquid-phase imaging of chemical processes with single-atom precision.
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9
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Pan Y, Zhao Q, Gao F, Dai M, Gao W, Zheng T, Su S, Li J, Chen H. Strong In-Plane Optical and Electrical Anisotropies of Multilayered γ-InSe for High-Responsivity Polarization-Sensitive Photodetectors. ACS APPLIED MATERIALS & INTERFACES 2022; 14:21383-21391. [PMID: 35482007 DOI: 10.1021/acsami.2c04204] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Recently, identifying promising new two-dimensional (2D) materials with low-symmetry structures has aroused great interest for developing monolithic polarization-sensitive photodetectors with small volume. Here, after comprehensive research of the in-plane anisotropic structure and electronic and optoelectronic properties of layered γ-InSe, a superior responsivity polarization-sensitive photodetector based on multilayer γ-InSe is constructed by a facile method. Notably, the conductance and carrier mobility of the device along the armchair direction are 11.8 and 2.35 times larger than those along the zigzag direction, respectively. Benefitting from the high efficiency of light absorption and excellent carrier mobility (221 cm2 V-1 s-1) of our multilayered γ-InSe along the armchair direction, the device exhibits a superior responsivity of 127 A/W and an external quantum efficiency (EQE) of 104%. Especially, the highest responsivity along the armchair direction of our γ-InSe polarization-sensitive photodetectors can reach as high as 78.5 A/W under polarized light. This value is much higher than those of other devices even under unpolarized light. This work not only provides an insight into the in-plane anisotropic properties of 2D layered γ-InSe but also proposes a stable and environmentally friendly candidate for anisotropic optoelectronic applications.
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Affiliation(s)
- Yuan Pan
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
| | - Qixiao Zhao
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
| | - Feng Gao
- Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education, Harbin Institute of Technology, Harbin 150080, P. R. China
| | - Mingjin Dai
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Wei Gao
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
| | - Tao Zheng
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
| | - Shichen Su
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
- SCNU Qingyuan Institute of Science and Technology Innovation Co., Ltd., Qingyuan 511517, P. R. China
| | - Jingbo Li
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
| | - Hongyu Chen
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China
- Guangdong Province Key Lab of Chip and Integration Technology, Guangzhou 510631, P. R. China
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10
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Zhu W, Lin H, Yan F, Hu C, Wang Z, Zhao L, Deng Y, Kudrynskyi ZR, Zhou T, Kovalyuk ZD, Zheng Y, Patanè A, Žutić I, Li S, Zheng H, Wang K. Large Tunneling Magnetoresistance in van der Waals Ferromagnet/Semiconductor Heterojunctions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104658. [PMID: 34642998 DOI: 10.1002/adma.202104658] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/01/2021] [Indexed: 06/13/2023]
Abstract
2D layered chalcogenide semiconductors have been proposed as a promising class of materials for low-dimensional electronic, optoelectronic, and spintronic devices. Here, all-2D van der Waals vertical spin-valve devices, that combine the 2D layered semiconductor InSe as a spacer with the 2D layered ferromagnetic metal Fe3 GeTe2 as spin injection and detection electrodes, are reported. Two distinct transport behaviors are observed: tunneling and metallic, which are assigned to the formation of a pinhole-free tunnel barrier at the Fe3 GeTe2 /InSe interface and pinholes in the InSe spacer layer, respectively. For the tunneling device, a large magnetoresistance (MR) of 41% is obtained under an applied bias current of 0.1 µA at 10 K, which is about three times larger than that of the metallic device. Moreover, the tunneling device exhibits a lower operating bias current but a more sensitive bias current dependence than the metallic device. The MR and spin polarization of both the metallic and tunneling devices decrease with increasing temperature, which can be fitted well by Bloch's law. These findings reveal the critical role of pinholes in the MR of all-2D van der Waals ferromagnet/semiconductor heterojunction devices.
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Affiliation(s)
- Wenkai Zhu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hailong Lin
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Faguang Yan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
| | - Ce Hu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ziao Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lixia Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Tiangong University, Tianjin, 300387, China
| | - Yongcheng Deng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zakhar R Kudrynskyi
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Tong Zhou
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA
| | - Zakhar D Kovalyuk
- Frantsevich Institute for Problems of Materials Science, The National Academy of Sciences of Ukraine, Chernivtsi Branch, Chernivtsi, 58001, Ukraine
| | - Yuanhui Zheng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Amalia Patanè
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Igor Žutić
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA
| | - Shushen Li
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Houzhi Zheng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kaiyou Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
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11
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Salomone M, Re Fiorentin M, Cicero G, Risplendi F. Point Defects in Two-Dimensional Indium Selenide as Tunable Single-Photon Sources. J Phys Chem Lett 2021; 12:10947-10952. [PMID: 34735143 PMCID: PMC8607502 DOI: 10.1021/acs.jpclett.1c02912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/18/2021] [Accepted: 10/27/2021] [Indexed: 06/13/2023]
Abstract
In the past few years remarkable interest has been kindled by the development of nonclassical light sources and, in particular, of single-photon emitters (SPE), which represent fundamental building blocks for optical quantum technology. In this Letter, we analyze the stability and electronic properties of an InSe monolayer with point defects with the aim of demonstrating its applicability as an SPE. The presence of deep defect states within the InSe band gap is verified when considering substitutional defects with atoms belonging to group IV, V, and VI. In particular, the optical properties of Ge as substitution impurity of Se predicted by solving the Bethe-Salpeter equation on top of the GW corrected electronic states show that transitions between the valence band maximum and the defect state are responsible for the absorption and spontaneous emission processes, so that the latter results in a strongly peaked spectrum in the near-infrared. These properties, together with a high localization of the involved electronic states, appear encouraging in the quest for novel SPE materials.
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Affiliation(s)
- Mattia Salomone
- Dipartimento
di Scienza Applicata e Tecnologia, Politecnico
di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Michele Re Fiorentin
- Center
for Sustainable Future Technologies, Istituto
Italiano di Tecnologia, via Livorno 60, 10144 Torino, Italy
| | - Giancarlo Cicero
- Dipartimento
di Scienza Applicata e Tecnologia, Politecnico
di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Francesca Risplendi
- Dipartimento
di Scienza Applicata e Tecnologia, Politecnico
di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy
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12
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Hopkinson DG, Seki T, Clark N, Chen R, Zou Y, Kimura A, Gorbachev RV, Thomson T, Shibata N, Haigh SJ. Nanometre imaging of Fe 3GeTe 2 ferromagnetic domain walls. NANOTECHNOLOGY 2021; 32:205703. [PMID: 33624615 DOI: 10.1088/1361-6528/abe32b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fe3GeTe2 is a layered crystal which has recently been shown to maintain its itinerant ferromagnetic properties even when atomically thin. Here, differential phase contrast scanning transmission electron microscopy is used to investigate the domain structure in a Fe3GeTe2 cross-sectional lamella at temperatures ranging from 95 to 250 K and at nanometre spatial resolution. Below the experimentally determined Curie temperature (T C) of 191 K, stripe domains magnetised along 〈0001〉, bounded with 180◦ Bloch type domain walls, are observed, transitioning to mixed Bloch-Néel type where the cross-sectional thickness is reduced below 50 nm. When warming towards T C, these domains undergo slight restructuring towards uniform size, before abruptly fading at T C. Localised loss of ferromagnetic order is seen over time, hypothesised to be a frustration of ferromagnetic order from ambient oxidation and basal cracking, which could enable selective modification of the magnetic properties for device applications.
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Affiliation(s)
- David G Hopkinson
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Takehito Seki
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Nicholas Clark
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Runze Chen
- Department of Computer Science, The University of Manchester, M13 9PL, United Kingdom
| | - Yichao Zou
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
| | - Ayumi Kimura
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - Roman V Gorbachev
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Physics & Astronomy, The University of Manchester, M13 9PL, United Kingdom
| | - Thomas Thomson
- Department of Computer Science, The University of Manchester, M13 9PL, United Kingdom
| | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, Atsuta, Nagoya 456-8587, Japan
| | - Sarah J Haigh
- National Graphene Institute, The University of Manchester, M13 9PL, United Kingdom
- Department of Materials, The University of Manchester, M13 9PL, United Kingdom
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13
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Zhang T, Liang Y, Guo H, Zhang TC, Fan H, Tian X. The interaction between vacancy defects in gallium sulfide monolayer and a new vacancy defect model. Phys Chem Chem Phys 2021; 23:13623-13632. [PMID: 34115084 DOI: 10.1039/d1cp01194d] [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
Vacancy defects are inevitable when synthesizing two-dimensional (2D) materials, and vacancy defects greatly affect the physical properties, such as magnetism and electronic properties. Currently, sufficient information is not available on whether and how the interaction of vacancy defects affects material properties and how to control these defects and their associated interaction for the development of new materials. In this study, the interaction between two adjacent vacancy defects of the gallium sulfide (GaS) monolayer is investigated using first-principles calculations based on density functional theory (DFT). The results indicate that the localized size of a Ga vacancy defect is the area within the S atoms second nearest to the neighboring vacancy defect. When the localized sizes of Ga vacancy defects intersect, a non-negligible interaction exists between the Ga vacancy defects. The interaction generally has been ignored by the traditional defect concentrations model but would affect the magnetic and electronic properties of the defective GaS monolayer. A vacancy defect cluster model (VDCM) is developed based on the system clustering method and then used to evaluate the interactions between vacancy defects. In order to check the reliability of the model, this research studies a defective MoS2 monolayer as an example and compares the band gap and density of states (DOS) calculated by using different vacancy defect models, including VDCM. The results indicate that VDCM has good accuracy relative to the traditional vacancy concentration model. This means that with the help of VDCM the properties of the defective system could be calculated more accurately considering some extent of nonuniform distribution of defects based on DFT.
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Affiliation(s)
- Tao Zhang
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. and College of Architecture & Environment, Sichuan University, Chengdu, Sichuan 610065, China
| | - Ying Liang
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. and College of Architecture & Environment, Sichuan University, Chengdu, Sichuan 610065, China
| | - Hao Guo
- College of Architecture & Environment, Sichuan University, Chengdu, Sichuan 610065, China
| | - Tian C Zhang
- Civil & Environmental Engineering Department, University of Nebraska-Lincoln, Omaha, NE 68182-0178, USA
| | - Haidong Fan
- College of Architecture & Environment, Sichuan University, Chengdu, Sichuan 610065, China
| | - Xiaobao Tian
- MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China. and College of Architecture & Environment, Sichuan University, Chengdu, Sichuan 610065, China
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14
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Kumar AS, Wang M, Li Y, Fujita R, Gao XPA. Interfacial Charge Transfer and Gate-Induced Hysteresis in Monochalcogenide InSe/GaSe Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2020; 12:46854-46861. [PMID: 32955239 DOI: 10.1021/acsami.0c09635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Heterostructures of two-dimensional (2D) van der Waals semiconductor materials offer a diverse playground for exploring fundamental physics and potential device applications. In InSe/GaSe heterostructures formed by sequential mechanical exfoliation and stacking of 2D monochalcogenides InSe and GaSe, we observe charge transfer between InSe and GaSe because of the 2D van der Waals interface formation and a strong hysteresis effect in the electron transport through the InSe layer when a gate voltage is applied through the GaSe layer. A gate voltage-dependent conductance decay rate is also observed. We relate these observations to the gate voltage-dependent dynamical charge transfer between InSe and GaSe layers.
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Affiliation(s)
- Arvind Shankar Kumar
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Mingyuan Wang
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Yancheng Li
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Ryuji Fujita
- Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU, U.K
| | - Xuan P A Gao
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, United States
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15
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Hamer MJ, Hopkinson DG, Clark N, Zhou M, Wang W, Zou Y, Kelly DJ, Bointon TH, Haigh SJ, Gorbachev RV. Atomic Resolution Imaging of CrBr 3 Using Adhesion-Enhanced Grids. NANO LETTERS 2020; 20:6582-6589. [PMID: 32786938 DOI: 10.1021/acs.nanolett.0c02346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Suspended specimens of 2D crystals and their heterostructures are required for a range of studies including transmission electron microscopy (TEM), optical transmission experiments, and nanomechanical testing. However, investigating the properties of laterally small 2D crystal specimens, including twisted bilayers and air-sensitive materials, has been held back by the difficulty of fabricating the necessary clean suspended samples. Here we present a scalable solution that allows clean free-standing specimens to be realized with 100% yield by dry-stamping atomically thin 2D stacks onto a specially developed adhesion-enhanced support grid. Using this new capability, we demonstrate atomic resolution imaging of defect structures in atomically thin CrBr3, a novel magnetic material that degrades in ambient conditions.
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Affiliation(s)
- Matthew J Hamer
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - David G Hopkinson
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Nick Clark
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Mingwei Zhou
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Wendong Wang
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Yichao Zou
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Daniel J Kelly
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Thomas H Bointon
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sarah J Haigh
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Roman V Gorbachev
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Henry Royce Institute, Oxford Road, Manchester M13 9PL, United Kingdom
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16
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Deák P, Han M, Lorke M, Tabriz MF, Frauenheim T. Intrinsic defects of GaSe. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:285503. [PMID: 32168498 DOI: 10.1088/1361-648x/ab7fdb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
GaSe is a layered semiconductor with an optical band gap tunable by the number of layers in a thin film. This is promising for application in micro/optoelectronics and photovoltaics. However, for that, knowledge about the intrinsic defects are needed, since they may influence device behavior. Here we present a comprehensive study of intrinsic point defects in both bulk and monolayer (ML) GaSe, using an optimized hybrid functional which reproduces the band gap and is Koopmans' compliant. Formation energies and charge transition levels are calculated, the latter in good agreement with available experimental data. We find that the only intrinsic donor is the interlayer gallium interstitial, which is absent in the case of the ML. The vacancies are acceptors, the selenium interstitial is electrically inactive, and small intrinsic defect complexes have formation energies too high to play a role in the electronic properties of samples grown under quasi-equilibrium conditions. Bulk GaSe is well compensated by the intrinsic defects, and is an ideal substrate. The ML is intrinsically p-type, and p-type doping cannot be compensated either. The opening of the band gap changes the defect physics considerably with respect to the bulk.
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Affiliation(s)
- Peter Deák
- Bremen Center for Computational Materials Sci., University of Bremen, PoB 330440, D-28334 Bremen, Germany
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