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Lin CY, Chen CF, Chang YM, Yang SH, Lee KC, Wu WW, Jian WB, Lin YF. A Triode Device with a Gate Controllable Schottky Barrier: Germanium Nanowire Transistors and Their Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900865. [PMID: 31264786 DOI: 10.1002/smll.201900865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 06/12/2019] [Indexed: 06/09/2023]
Abstract
Electrical contacts often dominate charge transport properties at the nanoscale because of considerable differences in nanoelectronic device interfaces arising from unique geometric and electrostatic features. Transistors with a tunable Schottky barrier between the metal and semiconductor interface might simplify circuit design. Here, germanium nanowire (Ge NW) transistors with Cu3 Ge as source/drain contacts formed by both buffered oxide etching treatments and rapid thermal annealing are reported. The transistors based on this Cu3 Ge/Ge/Cu3 Ge heterostructure show ambipolar transistor behavior with a large on/off current ratio of more than 105 and 103 for the hole and electron regimes at room temperature, respectively. Investigations of temperature-dependent transport properties and low-frequency current fluctuations reveal that the tunable effective Schottky barriers of the Ge NW transistors accounted for the ambipolar behaviors. It is further shown that this ambipolarity can be used to realize binary-signal and data-storage functions, which greatly simplify circuit design compared with conventional technologies.
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Affiliation(s)
- Che-Yi Lin
- Department of Electrophysics, National Chiao Tung University, Hsinchu, 300, Taiwan
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chao-Fu Chen
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yuan-Ming Chang
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Shih-Hsien Yang
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Department of Electrical Engineering and Institute of Electronic Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Ko-Chun Lee
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Department of Electrical Engineering and Institute of Electronic Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Wen-Wei Wu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
- Center for the Intelligent Semiconductor Nano-system Technology Research, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Wen-Bin Jian
- Department of Electrophysics, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Yen-Fu Lin
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Institute of Nanoscience, National Chung Hsing University, Taichung, 40227, Taiwan
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2
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Kountouriotis K, Barreda JL, Keiper TD, Zhang M, Xiong P. Electrical Spin Injection and Detection in Silicon Nanowires with Axial Doping Gradient. NANO LETTERS 2018; 18:4386-4395. [PMID: 29898367 DOI: 10.1021/acs.nanolett.8b01423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interest in spin transport in nanoscopic semiconductor channels is driven by both the inevitable miniaturization of spintronics devices toward nanoscale and the rich spin-dependent physics the quantum confinement engenders. For such studies, the all-important issue of the ferromagnet/semiconductor (FM/SC) interface becomes even more critical at nanoscale. Here we elucidate the effects of the FM/SC interface on electrical spin injection and detection at nanoscale dimensions, utilizing a unique type of Si nanowires (NWs) with an inherent axial doping gradient. Two-terminal and nonlocal four-terminal lateral spin-valve measurements were performed using different combinations from a series of FM contacts positioned along the same NW. The data are analyzed with a general model of spin accumulation in a normal channel under electrical spin injection from a FM, which reveals a distinct correlation of decreasing spin-valve signal with increasing injector junction resistance. The observation is attributed to the diminishing contribution of the d-electrons in the FM to the injected current spin polarization with increasing Schottky barrier width. The results demonstrate that there is a window of interface parameters for optimal spin injection efficiency and current spin polarization, which provides important design guidelines for nanospintronic devices with quasi-one-dimensional semiconductor channels.
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Affiliation(s)
| | - Jorge L Barreda
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
| | - Timothy D Keiper
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
| | - Mei Zhang
- Department of Industrial and Manufacturing Engineering, College of Engineering , Florida A&M University-Florida State University (FAMU-FSU) , Tallahassee , Florida 32310 , United States
| | - Peng Xiong
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
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3
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Park TE, Park YH, Lee JM, Kim SW, Park HG, Min BC, Kim HJ, Koo HC, Choi HJ, Han SH, Johnson M, Chang J. Large spin accumulation and crystallographic dependence of spin transport in single crystal gallium nitride nanowires. Nat Commun 2017; 8:15722. [PMID: 28569767 PMCID: PMC5461503 DOI: 10.1038/ncomms15722] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/24/2017] [Indexed: 11/09/2022] Open
Abstract
Semiconductor spintronics is an alternative to conventional electronics that offers devices with high performance, low power and multiple functionality. Although a large number of devices with mesoscopic dimensions have been successfully demonstrated at low temperatures for decades, room-temperature operation still needs to go further. Here we study spin injection in single-crystal gallium nitride nanowires and report robust spin accumulation at room temperature with enhanced spin injection polarization of 9%. A large Overhauser coupling between the electron spin accumulation and the lattice nuclei is observed. Finally, our single-crystal gallium nitride samples have a trigonal cross-section defined by the (001), () and () planes. Using the Hanle effect, we show that the spin accumulation is significantly different for injection across the (001) and () (or ()) planes. This provides a technique for increasing room temperature spin injection in mesoscopic systems.
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Affiliation(s)
- Tae-Eon Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Youn Ho Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Jong-Min Lee
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Sung Wook Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Hee Gyum Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
| | - Byoung-Chul Min
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
| | - Hyung-Jun Kim
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Hyun Cheol Koo
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Heon-Jin Choi
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Suk Hee Han
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Mark Johnson
- Naval Research Laboratory, Washington, District Of Columbia 20375, USA
| | - Joonyeon Chang
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
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4
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Bottegoni F, Zucchetti C, Dal Conte S, Frigerio J, Carpene E, Vergnaud C, Jamet M, Isella G, Ciccacci F, Cerullo G, Finazzi M. Spin-Hall Voltage over a Large Length Scale in Bulk Germanium. PHYSICAL REVIEW LETTERS 2017; 118:167402. [PMID: 28474919 DOI: 10.1103/physrevlett.118.167402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Indexed: 06/07/2023]
Abstract
We exploit the spin-Hall effect to generate a uniform pure spin current in an epitaxial n-doped Ge channel, and we detect the electrically induced spin accumulation, transverse to the injected charge current density, with polar magneto-optical Kerr microscopy at a low temperature. We show that a large spin density up to 400 μm^{-3} can be achieved at the edges of the 100-μm-wide Ge channel for an applied electric field lower than 5 mV/μm. We find that the spin density linearly decreases toward the center of the Ge bar, due to the large spin diffusion length, and such a decay is much slower than the exponential one observed in III-V semiconductors, allowing very large spin accumulations over a length scale of tens of micrometers. This lays the foundation for multiterminal spintronic devices, where different spin voltages can be exploited as inputs for magnetologic gates on the same Ge platform.
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Affiliation(s)
- F Bottegoni
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - C Zucchetti
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - S Dal Conte
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - J Frigerio
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - E Carpene
- IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - C Vergnaud
- Université Grenoble Alpes, INAC-SPINTEC, F38000 Grenoble, France
- CEA-INAC-SPINTEC, F38054 Grenoble, France
| | - M Jamet
- Université Grenoble Alpes, INAC-SPINTEC, F38000 Grenoble, France
- CEA-INAC-SPINTEC, F38054 Grenoble, France
| | - G Isella
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - F Ciccacci
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - G Cerullo
- IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - M Finazzi
- LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
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5
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Modepalli V, Jin MJ, Park J, Jo J, Kim JH, Baik JM, Seo C, Kim J, Yoo JW. Gate-Tunable Spin Exchange Interactions and Inversion of Magnetoresistance in Single Ferromagnetic ZnO Nanowires. ACS NANO 2016; 10:4618-4626. [PMID: 26964013 DOI: 10.1021/acsnano.6b00921] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrical control of ferromagnetism in semiconductor nanostructures offers the promise of nonvolatile functionality in future semiconductor spintronics. Here, we demonstrate a dramatic gate-induced change of ferromagnetism in ZnO nanowire (NW) field-effect transistors (FETs). Ferromagnetism in our ZnO NWs arose from oxygen vacancies, which constitute deep levels hosting unpaired electron spins. The magnetic transition temperature of the studied ZnO NWs was estimated to be well above room temperature. The in situ UV confocal photoluminescence (PL) study confirmed oxygen vacancy mediated ferromagnetism in the studied ZnO NW FET devices. Both the estimated carrier concentration and temperature-dependent conductivity reveal the studied ZnO NWs are at the crossover of the metal-insulator transition. In particular, gate-induced modulation of the carrier concentration in the ZnO NW FET significantly alters carrier-mediated exchange interactions, which causes even inversion of magnetoresistance (MR) from negative to positive values. Upon sweeping the gate bias from -40 to +50 V, the MRs estimated at 2 K and 2 T were changed from -11.3% to +4.1%. Detailed analysis on the gate-dependent MR behavior clearly showed enhanced spin splitting energy with increasing carrier concentration. Gate-voltage-dependent PL spectra of an individual NW device confirmed the localization of oxygen vacancy-induced spins, indicating that gate-tunable indirect exchange coupling between localized magnetic moments played an important role in the remarkable change of the MR.
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Affiliation(s)
- Vijayakumar Modepalli
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Mi-Jin Jin
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Jungmin Park
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Junhyeon Jo
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Ji-Hyun Kim
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Jeong Min Baik
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Changwon Seo
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - Jeongyong Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
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6
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Simon P, Wolf D, Wang C, Levin AA, Lubk A, Sturm S, Lichte H, Fecher GH, Felser C. Synthesis and Three-Dimensional Magnetic Field Mapping of Co2FeGa Heusler Nanowires at 5 nm Resolution. NANO LETTERS 2016; 16:114-120. [PMID: 26674206 DOI: 10.1021/acs.nanolett.5b03102] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present the synthesis of Co2FeGa Heusler nanowires and the results of our investigations on their three-dimensional (3D) electric and magnetic internal and external fields mapped by electron holographic tomography (EHT). These fields will be of great importance in next-generation nanomagnets integrated in spintronics and memory devices. The Co2FeGa nanowires with a L21 ordered structure are prepared by a SBA-15 silica-assisted method. The magnetic dipole-like stray fields of several Co2FeGa nanowires are revealed by holographically reconstructed phase images. Based on the measured magnetic phase shifts of an individual nanowire and its 3D reconstruction using EHT, we obtain an internal magnetic induction with a magnitude of 1.15 T and a nonmagnetic surface layer of 10 nm thickness. Furthermore, we also reconstruct the 3D distribution of the electrostatic potential of the same nanowire.
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Affiliation(s)
- Paul Simon
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Daniel Wolf
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Changhai Wang
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Aleksandr A Levin
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Axel Lubk
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Sebastian Sturm
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Hannes Lichte
- Institute of Structure Physics, Triebenberg Laboratory, Technical University of Dresden , Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany
| | - Gerhard H Fecher
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Claudia Felser
- Max-Planck-Institut für Chemische Physik fester Stoffe , Nöthnitzer Str. 40, 01187 Dresden, Germany
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7
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Wang Z, Pan D, Wang L, Wang T, Zhao B, Wu Y, Yang M, Xu X, Miao J, Zhao J, Jiang Y. Room-temperature spin transport in InAs nanowire lateral spin valve. RSC Adv 2016. [DOI: 10.1039/c6ra13516a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report room temperature spin transport in an InAs nanowire device. A large spin signal of 35 kΩ and long spin diffusion length of 1.9 μm are achieved. We believe that these results open a practical way to design InAs NW based spintronic devices.
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8
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van ’t Erve OMJ, Friedman AL, Li CH, Robinson JT, Connell J, Lauhon LJ, Jonker BT. Spin transport and Hanle effect in silicon nanowires using graphene tunnel barriers. Nat Commun 2015; 6:7541. [DOI: 10.1038/ncomms8541] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 05/16/2015] [Indexed: 11/09/2022] Open
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9
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Tang J, Wang KL. Electrical spin injection and transport in semiconductor nanowires: challenges, progress and perspectives. NANOSCALE 2015; 7:4325-4337. [PMID: 25686092 DOI: 10.1039/c4nr07611g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Spintronic devices are of fundamental interest for their nonvolatility and great potential for low-power electronics applications. The implementation of those devices usually favors materials with long spin lifetime and spin diffusion length. Recent spin transport studies on semiconductor nanowires have shown much longer spin lifetimes and spin diffusion lengths than those reported in bulk/thin films. In this paper, we have reviewed recent progress in the electrical spin injection and transport in semiconductor nanowires and drawn a comparison with that in bulk/thin films. In particular, the challenges and methods of making high-quality ferromagnetic tunneling and Schottky contacts on semiconductor nanowires as well as thin films are discussed. Besides, commonly used methods for characterizing spin transport have been introduced, and their applicability in nanowire devices are discussed. Moreover, the effect of spin-orbit interaction strength and dimensionality on the spin relaxation and hence the spin lifetime are investigated. Finally, for further device applications, we have examined several proposals of spinFETs and provided a perspective of future studies on semiconductor spintronics.
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Affiliation(s)
- Jianshi Tang
- Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA.
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10
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Li P, Li J, Qing L, Dery H, Appelbaum I. Anisotropy-driven spin relaxation in germanium. PHYSICAL REVIEW LETTERS 2013; 111:257204. [PMID: 24483755 DOI: 10.1103/physrevlett.111.257204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Indexed: 06/03/2023]
Abstract
A unique spin depolarization mechanism, induced by the presence of g-factor anisotropy and intervalley scattering, is revealed by spin-transport measurements on long-distance germanium devices in a magnetic field longitudinal to the initial spin orientation. The confluence of electron-phonon scattering (leading to Elliott-Yafet spin flips) and this previously unobserved physics enables the extraction of spin lifetime solely from spin-valve measurements, without spin precession, and in a regime of substantial electric-field-generated carrier heating. We find spin lifetimes in Ge up to several hundreds of nanoseconds at low temperature, far beyond any other available experimental results.
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Affiliation(s)
- Pengke Li
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA and Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA
| | - Jing Li
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA
| | - Lan Qing
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Hanan Dery
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - Ian Appelbaum
- Department of Physics and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA
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11
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Tang J, Wang CY, Chang LT, Fan Y, Nie T, Chan M, Jiang W, Chen YT, Yang HJ, Tuan HY, Chen LJ, Wang KL. Electrical spin injection and detection in Mn5Ge3/Ge/Mn5Ge3 nanowire transistors. NANO LETTERS 2013; 13:4036-4043. [PMID: 23937588 DOI: 10.1021/nl401238p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this Letter, we report the electrical spin injection and detection in Ge nanowire transistors with single-crystalline ferromagnetic Mn5Ge3 as source/drain contacts formed by thermal reactions. Degenerate indium dopants were successfully incorporated into as-grown Ge nanowires as p-type doping to alleviate the conductivity mismatch between Ge and Mn5Ge3. The magnetoresistance (MR) of the Mn5Ge3/Ge/Mn5Ge3 nanowire transistor was found to be largely affected by the applied bias. Specifically, negative and hysteretic MR curves were observed under a large current bias in the temperature range from T = 2 K up to T = 50 K, which clearly indicated the electrical spin injection from ferromagnetic Mn5Ge3 contacts into Ge nanowires. In addition to the bias effect, the MR amplitude was found to exponentially decay with the Ge nanowire channel length; this fact was explained by the dominated Elliot-Yafet spin-relaxation mechanism. The fitting of MR further revealed a spin diffusion length of lsf = 480 ± 13 nm and a spin lifetime exceeding 244 ps at T = 10 K in p-type Ge nanowires, and they showed a weak temperature dependence between 2 and 50 K. Ge nanowires showed a significant enhancement in the measured spin diffusion length and spin lifetime compared with those reported for bulk p-type Ge. Our study of the spin transport in the Mn5Ge3/Ge/Mn5Ge3 nanowire transistor points to a possible realization of spin-based transistors; it may also open up new opportunities to create novel Ge nanowire-based spintronic devices. Furthermore, the simple fabrication process promises a compatible integration into standard Si technology in the future.
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Affiliation(s)
- Jianshi Tang
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles, California, 90095, United States
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12
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Zhang S, Dayeh SA, Li Y, Crooker SA, Smith DL, Picraux ST. Electrical spin injection and detection in silicon nanowires through oxide tunnel barriers. NANO LETTERS 2013; 13:430-435. [PMID: 23324028 DOI: 10.1021/nl303667v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate all-electrical spin injection, transport, and detection in heavily n-type-doped Si nanowires using ferromagnetic Co/Al(2)O(3) tunnel barrier contacts. Analysis of both local and nonlocal spin valve signals at 4 K on the same nanowire device using a standard spin-transport model suggests that high spin injection efficiency (up to ~30%) and long spin diffusion lengths (up to ~6 μm) are achieved. These values exceed those reported for spin transport devices based on comparably doped bulk Si. The spin valve signals are found to be strongly bias and temperature dependent and can invert sign with changes in the dc bias current. The influence of the nanowire morphology on field-dependent switching of the contacts is also discussed. Owing to their nanoscale geometry, ~5 orders of magnitude less current is required to achieve nonlocal spin valve voltages comparable to those attained in planar microscale spin transport devices, suggesting lower power consumption and the potential for applications of Si nanowires in nanospintronics.
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Affiliation(s)
- Shixiong Zhang
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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13
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Vaughn II DD, Schaak RE. Synthesis, properties and applications of colloidal germanium and germanium-based nanomaterials. Chem Soc Rev 2013; 42:2861-79. [DOI: 10.1039/c2cs35364d] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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14
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Heedt S, Morgan C, Weis K, Bürgler DE, Calarco R, Hardtdegen H, Grützmacher D, Schäpers T. Electrical spin injection into InN semiconductor nanowires. NANO LETTERS 2012; 12:4437-4443. [PMID: 22889199 DOI: 10.1021/nl301052g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the conditions necessary for the electrical injection of spin-polarized electrons into indium nitride nanowires synthesized from the bottom up by molecular beam epitaxy. The presented results mark the first unequivocal evidence of spin injection into III-V semiconductor nanowires. Utilizing a newly developed preparation scheme, we are able to surmount shadowing effects during the metal deposition. Thus, we avoid strong local anisotropies that arise if the ferromagnetic leads are wrapping around the nanowire. Using a combination of various complementary techniques, inter alia the local Hall effect, we carried out a comprehensive investigation of the coercive fields and switching behaviors of the cobalt micromagnetic spin probes. This enables the identification of a range of aspect ratios in which the mechanism of magnetization reversal is single domain switching. Lateral nanowire spin valves were prepared. The spin relaxation length is demonstrated to be about 200 nm, which provides an incentive to pursue the route toward nanowire spin logic devices.
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Affiliation(s)
- S Heedt
- Peter Grünberg Institut (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany.
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15
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Tang J, Wang CY, Hung MH, Jiang X, Chang LT, He L, Liu PH, Yang HJ, Tuan HY, Chen LJ, Wang KL. Ferromagnetic germanide in Ge nanowire transistors for spintronics application. ACS NANO 2012; 6:5710-7. [PMID: 22658951 DOI: 10.1021/nn301956m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
To explore spintronics applications for Ge nanowire heterostructures formed by thermal annealing, it is critical to develop a ferromagnetic germanide with high Curie temperature and take advantage of the high-quality interface between Ge and the formed ferromagnetic germanide. In this work, we report, for the first time, the formation and characterization of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire transistors, in which the room-temperature ferromagnetic germanide was found through the solid-state reaction between a single-crystalline Ge nanowire and Mn contact pads upon thermal annealing. The atomically clean interface between Mn(5)Ge(3) and Ge with a relatively small lattice mismatch of 10.6% indicates that Mn(5)Ge(3) is a high-quality ferromagnetic contact to Ge. Temperature-dependent I-V measurements on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire heterostructure reveal a Schottky barrier height of 0.25 eV for the Mn(5)Ge(3) contact to p-type Ge. The Ge nanowire field-effect transistors built on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) heterostructure exhibit a high-performance p-type behavior with a current on/off ratio close to 10(5), and a hole mobility of 150-200 cm(2)/(V s). Temperature-dependent resistance of a fully germanided Mn(5)Ge(3) nanowire shows a clear transition behavior near the Curie temperature of Mn(5)Ge(3) at about 300 K. Our findings of the high-quality room-temperature ferromagnetic Mn(5)Ge(3) contact represent a promising step toward electrical spin injection into Ge nanowires and thus the realization of high-efficiency spintronic devices for room-temperature applications.
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Affiliation(s)
- Jianshi Tang
- Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
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Rinaldi C, Cantoni M, Petti D, Sottocorno A, Leone M, Caffrey NM, Sanvito S, Bertacco R. Ge-based spin-photodiodes for room-temperature integrated detection of photon helicity. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:3037-3041. [PMID: 22549940 DOI: 10.1002/adma.201104256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 02/07/2012] [Indexed: 05/31/2023]
Affiliation(s)
- Christian Rinaldi
- LNESS-Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
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Pezzoli F, Bottegoni F, Trivedi D, Ciccacci F, Giorgioni A, Li P, Cecchi S, Grilli E, Song Y, Guzzi M, Dery H, Isella G. Optical spin injection and spin lifetime in Ge heterostructures. PHYSICAL REVIEW LETTERS 2012; 108:156603. [PMID: 22587272 DOI: 10.1103/physrevlett.108.156603] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 11/15/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate optical orientation in Ge/SiGe quantum wells and study their spin properties. The ultrafast electron transfer from the center of the Brillouin zone to its edge allows us to achieve high spin polarizations and to resolve the spin dynamics of holes and electrons. The circular polarization degree of the direct gap photoluminescence exceeds the theoretical bulk limit, yielding ∼37% and ∼85% for transitions with heavy and light holes states, respectively. The spin lifetime of holes at the top of the valence band is estimated to be ∼0.5 ps and it is governed by transitions between light and heavy hole states. Electrons at the bottom of the conduction band, on the other hand, have a spin lifetime that exceeds 5 ns below 150 K. Theoretical analysis of the spin relaxation indicates that phonon-induced intervalley scattering dictates the spin lifetime of electrons.
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Affiliation(s)
- F Pezzoli
- LNESS-Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, I-20125 Milano, Italy.
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18
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Katsaros G, Golovach VN, Spathis P, Ares N, Stoffel M, Fournel F, Schmidt OG, Glazman LI, De Franceschi S. Observation of spin-selective tunneling in SiGe nanocrystals. PHYSICAL REVIEW LETTERS 2011; 107:246601. [PMID: 22243017 DOI: 10.1103/physrevlett.107.246601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Indexed: 05/14/2023]
Abstract
Spin-selective tunneling of holes in SiGe nanocrystals contacted by normal-metal leads is reported. The spin selectivity arises from an interplay of the orbital effect of the magnetic field with the strong spin-orbit interaction present in the valence band of the semiconductor. We demonstrate both experimentally and theoretically that spin-selective tunneling in semiconductor nanostructures can be achieved without the use of ferromagnetic contacts. The reported effect, which relies on mixing the light and heavy holes, should be observable in a broad class of quantum-dot systems formed in semiconductors with a degenerate valence band.
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Affiliation(s)
- G Katsaros
- SPSMS, CEA-INAC/UJF-Grenoble 1, 17 Rue des Martyrs, F-38054 Grenoble Cedex 9, France.
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Degrave JP, Schmitt AL, Selinsky RS, Higgins JM, Keavney DJ, Jin S. Spin polarization measurement of homogeneously doped Fe(1-x)Co(x)Si nanowires by Andreev reflection spectroscopy. NANO LETTERS 2011; 11:4431-4437. [PMID: 21923114 DOI: 10.1021/nl2026426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a general method for determining the spin polarization from nanowire materials using Andreev reflection spectroscopy implemented with a Nb superconducting contact and common electron-beam lithography device fabrication techniques. This method was applied to magnetic semiconducting Fe(1-x)Co(x)Si alloy nanowires with x̅ = 0.23, and the average spin polarization extracted from 6 nanowire devices is 28 ± 7% with a highest observed value of 35%. Local-electrode atom probe tomography (APT) confirms the homogeneous distribution of Co atoms in the FeSi host lattice, and X-ray magnetic circular dichroism (XMCD) establishes that the elemental origin of magnetism in this strongly correlated electron system is due to Co atoms.
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Affiliation(s)
- John P Degrave
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
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