In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in ...In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in air. During the measurement, a focused laser was used to heat one end of a freely suspended nanowire, with its other end embedded into a carbon conductive adhesive. In order to obtain the thermal conductivity of In As nanowires, the heat loss in the heat transfer process was estimated, which includes the heat loss through air conduction, the heat convection, and the radiation loss. The absorption ratio of the laser power in the In As nanowire was calculated. The result shows that the thermal conductivity of In As nanowires monotonically increases from 6.4 W m-1K-1to 10.5 W m-1K-1with diameters increasing from 100 nm to 190 nm, which is ascribed to the enhanced phonon-boundary scattering.展开更多
In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzit...In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzite structure and defect-free zinc blende structure InAs nanowires can be induced. It is found that these defect-free zinc blende structure InAs nanowires grow along 〈110〉 directions with four low-energy {111} and two {110} side-wall facets and adopt the (111) catalyst/nanowire interface. Our structural and chemical characterization and calculations identify the existence of a catalyst supersaturation threshold for the InAs nanowire growth. When the In concentration in the catalyst is sufficiently high, defect-free zinc blende structure InAs nanowires can be induced. This study provides an insight into the manipulation of crystal structure and structure quality of III-V semiconductor nanowires through catalyst engineering.展开更多
InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial ...InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial InAs nanowires,however,has often relied on the use of Au colloids which is non-CMOS compatible.Here,we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO_(2) substrates.The nanowires show superb electrical properties with field-effect electron mobility~2700 cm^(2)/Vs and ION/IOFF>10^(3).The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance,“printable”transistors,capable of delivering 510 mA ON currents(~400 nanowires).展开更多
High-density horizontal InAs nanowire transistors are fabricated on the interdigital silicon-on-insulator substrate.Hexagonal InAs nanowires are uniformly grown between face-to-face(111) vertical sidewalls of neighb...High-density horizontal InAs nanowire transistors are fabricated on the interdigital silicon-on-insulator substrate.Hexagonal InAs nanowires are uniformly grown between face-to-face(111) vertical sidewalls of neighboring Si fingers by metal–organic chemical vapor deposition. The density of InAs nanowires is high up to 32 per group of silicon fingers,namely an average of 4 nanowires per micrometer. The electrical characteristics with a higher on/off current ratio of 2×10~5are obtained at room temperature. The silicon-based horizontal InAs nanowire transistors are very promising for future high-performance circuits.展开更多
The high electron mobility has granted indium arsenide(InAs) nanowires(NWs) as an important class of nanomaterials for high performance electronics such as field-effect transistors(FETs).We reviewed recent progresses ...The high electron mobility has granted indium arsenide(InAs) nanowires(NWs) as an important class of nanomaterials for high performance electronics such as field-effect transistors(FETs).We reviewed recent progresses on the studies of quantum coherence,gate tunable one-dimensional(1D) confinement and spin orbit interaction(SOI) in InAs NW based electronic and thermoelectric transport devices.We also demonstrated gas sensing response of InAs NW FETs and elucidated the mechanism via a gating experiment.By using InAs NWs as an example,these fundamental transport studies have shed important lights on the potential thermoelectric,spintronic and gas sensing applications of semiconductor NWs where the 1D confinement,SOI or surface states effects are exploited.展开更多
InAs is a direct, narrow band gap (0.354 eV) material with ultrahigh electron mobility, and is potentially a good optoelectronic device candidate in the wide UV-visible-near-infrared region. In this work we report t...InAs is a direct, narrow band gap (0.354 eV) material with ultrahigh electron mobility, and is potentially a good optoelectronic device candidate in the wide UV-visible-near-infrared region. In this work we report the fabrication of InAs nanowire-based photodetectors, which showed a very high photoresponse over a broad spectral range from 300 to 1,100 nm. The responsivity, external quantum efficiency and detectivity of the device were respectively measured to be 4.4 × 103 AW , 1.03 × 106%, and 2.6 × 1011 Jones to visible incident light. Time dependent measurements at different wavelengths and under different light intensities also demonstrated the fast, reversible, and stable photoresponse of our device. Theoretical calculations of the optical absorption and the electric field component distribution were also performed to elucidate the mechanism of the enhanced photoresponse. Our results demonstrate that the single-crystalline InAs NWs are very promising candidates for the design of high sensitivity and high stability nanoscale photodetectors with a broad band photoresponse.展开更多
We demonstrate an original method based on controlled oxidation for creating high-quality tunnel junctions between superconducting A1 reservoirs and InAs semiconductor nanowires (NWs). We show clean tunnel character...We demonstrate an original method based on controlled oxidation for creating high-quality tunnel junctions between superconducting A1 reservoirs and InAs semiconductor nanowires (NWs). We show clean tunnel characteristics with a current suppression by 〉4 orders of magnitude for a junction bias well below the A1 gap of △0≈ 200 μeV. The experimental data agree well with the Bardeen- Cooper-Schrieffer theoretical expectations for a superconducting tunnel junction. The studied devices employ small-scale tunnel contacts functioning as thermometers as well as larger electrodes that provide proof-of-principle active cooling of the electron distribution in the NWs. A peak refrigeration of approximately δT = 10 mK is achieved at a bath temperature of Tbath≈ 250-350 mK for our prototype devices. This method introduces important perspectives for the investigation of the thermoelectric effects in semiconductor nanostructures and for nanoscale refrigeration.展开更多
基金the National Basic Research Program of China (No. 2012CB932703)the NSF of China (Nos. 11374092 and 11204073)+2 种基金the Research Fund for the Doctoral Program of Higher Education (Nos. 20110161110034, 20110161120027)the Fundamental Research Funds for Central Universities (Nos. xjj2011001 and 2012jdgz04)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (2013)
文摘In this work, we synthesized high-quality In As nanowires by a convenient chemical vapor deposition method,and developed a simple laser heating method to measure the thermal conductivity of a single In As nanowire in air. During the measurement, a focused laser was used to heat one end of a freely suspended nanowire, with its other end embedded into a carbon conductive adhesive. In order to obtain the thermal conductivity of In As nanowires, the heat loss in the heat transfer process was estimated, which includes the heat loss through air conduction, the heat convection, and the radiation loss. The absorption ratio of the laser power in the In As nanowire was calculated. The result shows that the thermal conductivity of In As nanowires monotonically increases from 6.4 W m-1K-1to 10.5 W m-1K-1with diameters increasing from 100 nm to 190 nm, which is ascribed to the enhanced phonon-boundary scattering.
文摘In this study, the structure and quality controlled growth of InAs nanowires using Au catalysts in a molecular beam epitaxy reactor is presented. By tuning the indium concentration in the catalyst, defect-free wurtzite structure and defect-free zinc blende structure InAs nanowires can be induced. It is found that these defect-free zinc blende structure InAs nanowires grow along 〈110〉 directions with four low-energy {111} and two {110} side-wall facets and adopt the (111) catalyst/nanowire interface. Our structural and chemical characterization and calculations identify the existence of a catalyst supersaturation threshold for the InAs nanowire growth. When the In concentration in the catalyst is sufficiently high, defect-free zinc blende structure InAs nanowires can be induced. This study provides an insight into the manipulation of crystal structure and structure quality of III-V semiconductor nanowires through catalyst engineering.
基金supported by MARCO/MSD Focus Center Research Program,Intel Corporation,Lawrence Berkeley National Laboratory,and an Intel Graduate Fellowship(J.C.H.).All fabrication was performed in the UC Berkeley Microlab facility.TEM imaging was performed at the Molecular Foundry,Lawrence Berkeley National Laboratory,which is supported by the Office of Science,Office of Basic Energy Sciences,U.S.Department of Energy,under Contract No.DE-AC02-05CH11231.
文摘InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation.The catalytic growth of nonepitaxial InAs nanowires,however,has often relied on the use of Au colloids which is non-CMOS compatible.Here,we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO_(2) substrates.The nanowires show superb electrical properties with field-effect electron mobility~2700 cm^(2)/Vs and ION/IOFF>10^(3).The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance,“printable”transistors,capable of delivering 510 mA ON currents(~400 nanowires).
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA02005003)the National Natural Science Foundation of China(Grant Nos.61376096 and 61327813)
文摘High-density horizontal InAs nanowire transistors are fabricated on the interdigital silicon-on-insulator substrate.Hexagonal InAs nanowires are uniformly grown between face-to-face(111) vertical sidewalls of neighboring Si fingers by metal–organic chemical vapor deposition. The density of InAs nanowires is high up to 32 per group of silicon fingers,namely an average of 4 nanowires per micrometer. The electrical characteristics with a higher on/off current ratio of 2×10~5are obtained at room temperature. The silicon-based horizontal InAs nanowire transistors are very promising for future high-performance circuits.
基金supported by National Natural Science Foundation of China,under Grant No.61428403the NSF CAREER Award Program(Grant No.DMR-1151534) for financial support of research at CWRU
文摘The high electron mobility has granted indium arsenide(InAs) nanowires(NWs) as an important class of nanomaterials for high performance electronics such as field-effect transistors(FETs).We reviewed recent progresses on the studies of quantum coherence,gate tunable one-dimensional(1D) confinement and spin orbit interaction(SOI) in InAs NW based electronic and thermoelectric transport devices.We also demonstrated gas sensing response of InAs NW FETs and elucidated the mechanism via a gating experiment.By using InAs NWs as an example,these fundamental transport studies have shed important lights on the potential thermoelectric,spintronic and gas sensing applications of semiconductor NWs where the 1D confinement,SOI or surface states effects are exploited.
基金Acknowledgements This work was supported by the National Natural Science Foundation (Nos. 91123008, 51002059, 21001046), the 973 Program of China (No. 2011CB933300), and the Program for New Century Excellent Talents of the Universities in China (grant No. NCET-11-0179). We thank the Analytical and Testing Center of Huazhong University of Science and Technology for measurements.
文摘InAs is a direct, narrow band gap (0.354 eV) material with ultrahigh electron mobility, and is potentially a good optoelectronic device candidate in the wide UV-visible-near-infrared region. In this work we report the fabrication of InAs nanowire-based photodetectors, which showed a very high photoresponse over a broad spectral range from 300 to 1,100 nm. The responsivity, external quantum efficiency and detectivity of the device were respectively measured to be 4.4 × 103 AW , 1.03 × 106%, and 2.6 × 1011 Jones to visible incident light. Time dependent measurements at different wavelengths and under different light intensities also demonstrated the fast, reversible, and stable photoresponse of our device. Theoretical calculations of the optical absorption and the electric field component distribution were also performed to elucidate the mechanism of the enhanced photoresponse. Our results demonstrate that the single-crystalline InAs NWs are very promising candidates for the design of high sensitivity and high stability nanoscale photodetectors with a broad band photoresponse.
文摘We demonstrate an original method based on controlled oxidation for creating high-quality tunnel junctions between superconducting A1 reservoirs and InAs semiconductor nanowires (NWs). We show clean tunnel characteristics with a current suppression by 〉4 orders of magnitude for a junction bias well below the A1 gap of △0≈ 200 μeV. The experimental data agree well with the Bardeen- Cooper-Schrieffer theoretical expectations for a superconducting tunnel junction. The studied devices employ small-scale tunnel contacts functioning as thermometers as well as larger electrodes that provide proof-of-principle active cooling of the electron distribution in the NWs. A peak refrigeration of approximately δT = 10 mK is achieved at a bath temperature of Tbath≈ 250-350 mK for our prototype devices. This method introduces important perspectives for the investigation of the thermoelectric effects in semiconductor nanostructures and for nanoscale refrigeration.