The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show th...The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-halfmaximum(FWHM) of rocking curves for the(0006) and(10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm-2, respectively, indicative of high single crystallinity. The out-ofplane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively.The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.展开更多
Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rec...Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rectifying characteristics with an ideality factor of 1.21, a forward current density(J) of 127.4 A/cm2 at 1.4 V, a specific on-state resistance(R_(on,sp)) of1.54 mΩ·cm^2,and an ultra-high on/off ratio of 2.1 ×10^(11) at±1 V. Due to a small depletion region in the highly-doped substrate, a breakdown feature was observed at-23 V, which corresponded to a breakdown field of 2.1 MV/cm and a power figure-of-merit(VB2/R_(on)) of 3.4×10~5 W/cm^2. Forward current-voltage characteristics were described well by the thermionic emission theory while thermionic field emission and trap-assisted tunneling were the dominant transport mechanisms at low and high reverse biases, respectively, which was a result of the contribution of deep-level traps at the metal-semiconductor interface. The presence of interfacial traps also caused the difference in Schottky barrier heights of 1.31 eV and 1.64 eV respectively determined by current-voltage and capacitance-voltage characteristics. With reduced trapping effect and incorporation of drift layers, the β-Ga_2 O_3 SBDs could further provide promising materials for delivering both high current output and high breakdown voltage.展开更多
Solar-blind photodetectors are of great interest to a wide range of industrial, civil, environmental, and biological applications. As one of the emerging ultrawide-bandgap semiconductors, gallium oxide(Ga_2O_3) exhibi...Solar-blind photodetectors are of great interest to a wide range of industrial, civil, environmental, and biological applications. As one of the emerging ultrawide-bandgap semiconductors, gallium oxide(Ga_2O_3) exhibits unique advantages over other wide-bandgap semiconductors, especially in developing high-performance solar-blind photodetectors. This paper comprehensively reviews the latest progresses of solar-blind photodetectors based on Ga_2O_3 materials in various forms of bulk single crystal, epitaxial films, nanostructures, and their ternary alloys.The basic working principles of photodetectors and the fundamental properties and synthesis of Ga_2O_3, as well as device processing developments, have been briefly summarized. A special focus is to address the physical mechanism for commonly observed huge photoconductive gains. Benefitting from the rapid development in material epitaxy and device processes, Ga_2O_3-based solar-blind detectors represent to date one of the most prospective solutions for UV detection technology towards versatile applications.展开更多
The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zi...The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells.Because of its nanoscale dimensions,mechanical flexibility,and minimal cytotoxicity to cells,the sensing module can be loaded in cells for long term in situ tracking with high sensitivity.A gradual increase in the nuclear refractive index during the apoptosis process is observed,revealing the increase in molecular density and the decrease in cell volume.The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.展开更多
Ferroelectric-semiconductor heterostructures offer an alternative strategy to manipulate polarization towards advanced devices with engineered functionality and improved performance.In this work,we report on the heter...Ferroelectric-semiconductor heterostructures offer an alternative strategy to manipulate polarization towards advanced devices with engineered functionality and improved performance.In this work,we report on the heteroepitaxial construction,band structure alignment and polarization engineering of the single-phasedκ-Ga_(2)O_(3)/GaN ferroelectric/polar heterojunction.A type-II band alignment is determined at theκ-Ga_(2)O_(3)/GaN polar hetero-interface,with a valence band offset of(1.74±0.1)eV and a conduction band offset of(0.29■0.1)eV.Besides the band edge discontinuity,charge dipoles induced by spontaneous polarization lead to the observed band bending with built-in potentials of 0.9 and 0.33 eV,respectively,at theκ-Ga_(2)O_(3)surface andκ-Ga_(2)O_(3)/GaN interface.The polarization switching properties of ferroelectricκ-Ga_(2)O_(3)are identified with a remanent polarization of approximately 2.7μC/cm^(2)via the direct hysteresis remanent polarization/voltage(P-V)loop measurement.These findings allow the rational design ofκ-Ga_(2)O_(3)ferroelectric/polar heterojunction for the application of power electronic devices,advanced memories and even ultra-low loss negative capacitance transistors.展开更多
Pursuing nanometer-scale nonlinear converters based on second harmonic generation(SHG)is a stimulating strategy for bio-sensing,on-chip optical circuits,and quantum information processing,but the light-conversion effi...Pursuing nanometer-scale nonlinear converters based on second harmonic generation(SHG)is a stimulating strategy for bio-sensing,on-chip optical circuits,and quantum information processing,but the light-conversion efficiency is still poor in such ultra-small dimensional nanostructures.Herein,we demonstrate a highly enhanced broadband frequency converter through a hybrid plasmonic–dielectric coupler,a ZnTe/ZnO single core–shell nanowire(NW)integrated with silver(Ag)nanoparticles(NPs).The NW dimension has been optimized to allow the engineering of dielectric resonances at both fundamental wave and second harmonic frequencies.Meanwhile,the localized surface plasmon resonances are excited in the regime between the Ag NPs and ZnTe/ZnO dielectric NW,as evidenced by plasmon-enhanced Raman scattering and resonant absorption.These two contributors remarkably enhance local fields and consequently support the strong broadband SHG outputs in this hybrid nanostructure by releasing stringent phase-matching conditions.The proposed nanoscale nonlinear optical converter enables the manipulation of nonlinear light–matter interactions toward the development of on-chip nanophotonic systems.展开更多
基金supported by the National Key Research and Development Project(No.2017YFB0403003)Shenzhen Fundamental Research Project(Nos.201773239,201888588)+4 种基金the National Natural Science Foundation of China(Nos.61774081,61322403)State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices(No.2017KF001)the Natural Science Foundation of Jiangsu Province(No.BK20161401)the Six Talent Peaks Project in Jiangsu Province(Mo.2014XXRJ001)the Fundamental Research Funds for the C entral Universities(Nos.021014380093,021014380085)
文摘The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-halfmaximum(FWHM) of rocking curves for the(0006) and(10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm-2, respectively, indicative of high single crystallinity. The out-ofplane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively.The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0403003)the National Natural Science Foundation of China(Grant Nos.61774081,61322403,and 91850112)+3 种基金the State Key R&D Project of Jiangsu,China(Grant No.BE2018115)Shenzhen Fundamental Research Project,China(Grant Nos.201773239 and 201888588)State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices,China(Grant No.2017KF001)the Fundamental Research Funds for the Central Universities,China(Grant Nos.021014380093 and 021014380085)
文摘Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rectifying characteristics with an ideality factor of 1.21, a forward current density(J) of 127.4 A/cm2 at 1.4 V, a specific on-state resistance(R_(on,sp)) of1.54 mΩ·cm^2,and an ultra-high on/off ratio of 2.1 ×10^(11) at±1 V. Due to a small depletion region in the highly-doped substrate, a breakdown feature was observed at-23 V, which corresponded to a breakdown field of 2.1 MV/cm and a power figure-of-merit(VB2/R_(on)) of 3.4×10~5 W/cm^2. Forward current-voltage characteristics were described well by the thermionic emission theory while thermionic field emission and trap-assisted tunneling were the dominant transport mechanisms at low and high reverse biases, respectively, which was a result of the contribution of deep-level traps at the metal-semiconductor interface. The presence of interfacial traps also caused the difference in Schottky barrier heights of 1.31 eV and 1.64 eV respectively determined by current-voltage and capacitance-voltage characteristics. With reduced trapping effect and incorporation of drift layers, the β-Ga_2 O_3 SBDs could further provide promising materials for delivering both high current output and high breakdown voltage.
基金supported by the National Key R&D Program of China(2022YFB3605400)the State Key Research and Development Project of Guangdong(2020B010174002)the National Natural Science Foundation of China(62234007,U21A20503 and U21A2071).
基金National Key Research and Development Project(2017YFB0403003,2018YFB0406502)National Natural Science Foundation of China(NSFC)(61322403,61774081)+4 种基金State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices(2017KF001)Natural Science Foundation of Jiangsu Province(BK20161401)State Key R&D Project of Jiangsu(BE2018115)Fundamental Research Funds for the Central Universities(021014380085,021014380093)Postgraduate Research and Practice Innovation Program of Jiangsu Province
文摘Solar-blind photodetectors are of great interest to a wide range of industrial, civil, environmental, and biological applications. As one of the emerging ultrawide-bandgap semiconductors, gallium oxide(Ga_2O_3) exhibits unique advantages over other wide-bandgap semiconductors, especially in developing high-performance solar-blind photodetectors. This paper comprehensively reviews the latest progresses of solar-blind photodetectors based on Ga_2O_3 materials in various forms of bulk single crystal, epitaxial films, nanostructures, and their ternary alloys.The basic working principles of photodetectors and the fundamental properties and synthesis of Ga_2O_3, as well as device processing developments, have been briefly summarized. A special focus is to address the physical mechanism for commonly observed huge photoconductive gains. Benefitting from the rapid development in material epitaxy and device processes, Ga_2O_3-based solar-blind detectors represent to date one of the most prospective solutions for UV detection technology towards versatile applications.
基金sponsored by the National Natural Science Foundation of China (Nos. 61925502 and 62135007)
文摘The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells.Because of its nanoscale dimensions,mechanical flexibility,and minimal cytotoxicity to cells,the sensing module can be loaded in cells for long term in situ tracking with high sensitivity.A gradual increase in the nuclear refractive index during the apoptosis process is observed,revealing the increase in molecular density and the decrease in cell volume.The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.
基金supported by the State Key Research and Development Project of Guangdong,China(Grant No.2020B010174002)the National Natural Science Foundation of China(Grant Nos.U21A20503,and U21A2071)。
文摘Ferroelectric-semiconductor heterostructures offer an alternative strategy to manipulate polarization towards advanced devices with engineered functionality and improved performance.In this work,we report on the heteroepitaxial construction,band structure alignment and polarization engineering of the single-phasedκ-Ga_(2)O_(3)/GaN ferroelectric/polar heterojunction.A type-II band alignment is determined at theκ-Ga_(2)O_(3)/GaN polar hetero-interface,with a valence band offset of(1.74±0.1)eV and a conduction band offset of(0.29■0.1)eV.Besides the band edge discontinuity,charge dipoles induced by spontaneous polarization lead to the observed band bending with built-in potentials of 0.9 and 0.33 eV,respectively,at theκ-Ga_(2)O_(3)surface andκ-Ga_(2)O_(3)/GaN interface.The polarization switching properties of ferroelectricκ-Ga_(2)O_(3)are identified with a remanent polarization of approximately 2.7μC/cm^(2)via the direct hysteresis remanent polarization/voltage(P-V)loop measurement.These findings allow the rational design ofκ-Ga_(2)O_(3)ferroelectric/polar heterojunction for the application of power electronic devices,advanced memories and even ultra-low loss negative capacitance transistors.
基金National Key Research and Development Program of China(2021YFB3600101)National Natural Science Foundation of China(91850112,U21A20503,U21A2071)+2 种基金Key-Area Research and Development Program of Guangdong Province(2020B010174002)Science and Technology Foundation of Guizhou Province(Qianke Foundation-ZK[2022]General 562)Master’s Degree Construction Project of Minzu Normal University of Xingyi(FZGHC2020-002).
文摘Pursuing nanometer-scale nonlinear converters based on second harmonic generation(SHG)is a stimulating strategy for bio-sensing,on-chip optical circuits,and quantum information processing,but the light-conversion efficiency is still poor in such ultra-small dimensional nanostructures.Herein,we demonstrate a highly enhanced broadband frequency converter through a hybrid plasmonic–dielectric coupler,a ZnTe/ZnO single core–shell nanowire(NW)integrated with silver(Ag)nanoparticles(NPs).The NW dimension has been optimized to allow the engineering of dielectric resonances at both fundamental wave and second harmonic frequencies.Meanwhile,the localized surface plasmon resonances are excited in the regime between the Ag NPs and ZnTe/ZnO dielectric NW,as evidenced by plasmon-enhanced Raman scattering and resonant absorption.These two contributors remarkably enhance local fields and consequently support the strong broadband SHG outputs in this hybrid nanostructure by releasing stringent phase-matching conditions.The proposed nanoscale nonlinear optical converter enables the manipulation of nonlinear light–matter interactions toward the development of on-chip nanophotonic systems.
