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Simulation of a new style vertical HVPE system

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Science China(Physics,Mechanics & Astronomy) 2012年第12期55卷 2434-2438页

作者： ZHOU An XIU XiangQian ZHANG Rong XIE ZiLi LIU Bin HAN Ping gu shulin SHI Yi ZHENG YouDou School of Physics Nanjing University Nanjing 210093 China Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and Engineering Nanjing University Nanjing 210093 China

In this paper,we simulate a new style vertical HVPE reactor by using computational fluid dynamics program *** order to find the best parameter on the growth rate of Gallium nitride(GaN),we change the distance between the inlet and the substrate,GaCl and NH3 inlets,and also we add substrate rotation *** the increase of the distance between the substrate and the gas inlet,GaN deposition rate decreases and the uniformity becomes *** results show that the optimal distance in this new-style vertical hydride vapour phase epitaxy(HVPE) system is 4 ***,as the distance between the GaCl inlet and the NH3 inlet changes,the uniformity of GaN deposition *** findings indicate that the optimal distance is 3 ***,it is found that substrate rotation also affects the growth rate of GaN.

关键词： GaN HVPE numerical simulation

Carrier transport and luminescence properties of n-type GaN

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 1046-1052页

作者： ZHANG Zeng ZHANG Rong XIE ZiLi LIU Bin XIU XiangQian JIANG RuoLian HAN Ping gu shulin SHI Yi ZHENG YouDou Key Laboratory of Advanced Photonic and Electronic Materials Department of PhysicsNanjing UniversityNanjing 210093China

The surface morphology,electrical properties and optical properties of Si doped n-type GaN were investigated. The intentional SiH4 doped GaN films were grown by metal organic chemical vapor deposition with the electron concentration varying from 3×1016 cm-3 to 5.4×1018 cm-3. The surface morphology shows that the roughness and dislocation pits increase as the mass flow rate of SiH4 increases,which indicates that the quality of GaN degrades gradually. The activation energy of Si in GaN with different n concentrations varies from 12 to 22 meV,which may originate from the interactions of donor wave functions. The carrier transport mechanism with increasing temperature from 100 to 420 K was concluded as the complex effect of both impurity scattering and phonon scattering. The position of the near band edge emission peak was determined by both renormalization of the band gap and B-M effect. The intensity variations of the yellow luminescence could be explained by the change of Ga vacancy concentration caused by Si doping.

关键词： n-type GaN morphology Hall-effect luminescence

The temperature dependence of optical properties of InGaN alloys

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Science China(Physics,Mechanics & Astronomy) 2012年第3期55卷 396-399页

作者： ZHAO ChuanZhen ZHANG Rong LIU Bin FU DeYi CHEN Hui LI Ming XIE ZiLi XIU XiangQian gu shulin ZHENG YouDou Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials Department of PhysicsNanjing National Laboratory of MicrostructuresNanjing UniversityNanjing 210093China School of Information and Communication Engineering Tianjin Polytechnics UniversityTianjin 300160China

In our experiments,the PL spectra of several In x Ga 1 x N alloy samples with In contents x=0.1,0.15 and 0.25 were measured as a function of temperature ranging from 10 K to 300 K.S-shaped temperature dependencies were observed in all InGaN samples and a sharp decrease in the full width at half maximum occurred with decreasing temperature in the moderate temperature *** was found that both phenomena are relative to localization *** addition,the degree of localization effects in three samples was investigated using the band-tail *** findings are presented in this paper.

关键词： InGaN photoluminescence full width at half maximum

Band alignment and polarization engineering inκ-Ga_(2)O_(3)/GaN ferroelectric heterojunction

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Science China(Physics,Mechanics & Astronomy) 2022年第7期65卷 147-152页

作者： Yanting Chen Hongkai Ning Yue Kuang Xing-Xing Yu He-He Gong Xuanhu Chen Fang-Fang Ren shulin gu Rong Zhang Youdou Zheng Xinran Wang Jiandong Ye School of Electronic Science and Engineering Nanjing UniversityNanjing 210023China

Ferroelectric-semiconductor heterostructures offer an alternative strategy to manipulate polarization towards advanced devices with engineered functionality and improved *** 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)*** 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 *** 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 *** 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.

关键词： wide-bandgap semiconductors ferroelectric polarization band alignment

Significant suppression of residual nitrogen incorporation in diamond film with a novel susceptor geometry employed in MPCVD

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Chinese Physics B 2022年第11期31卷 593-598页

作者： Weikang Zhao Yan Teng Kun Tang Shunming Zhu Kai Yang Jingjing Duan Yingmeng Huang Ziang Chen Jiandong Ye shulin gu School of Electronic Science&Engineering Nanjing UniversityNanjing 210046China

This work proposed to change the structure of the sample susceptor of the microwave plasma chemical vapor deposition(MPCVD)reaction chamber,that is,to introduce a small hole in the center of the susceptor to study its suppression effect on the incorporation of residual nitrogen in the MPCVD diamond *** using COMSOL multiphysics software simulation,the plasma characteristics and the concentration of chemical reactants in the cylindrical cavity of MPCVD system were studied,including electric field intensity,electron number density,electron temperature,the concentrations of atomic hydrogen,methyl,and nitrogenous substances,*** introducing a small hole in the center of the molybdenum support susceptor,we found that no significant changes were found in the center area of the plasma,but the electron state in the plasma changed greatly on the surface above the *** electron number density was reduced by about 40%,while the electron temperature was reduced by about 0.02 eV,and the concentration of atomic nitrogen was decreased by about an order of ***,we found that if a specific lower microwave input power is used,and a susceptor structure without the small hole is introduced,the change results similar to those in the surface area of the susceptor will be obtained,but the spatial distribution of electromagnetic field and reactant concentration will be changed.

关键词： plasma simulation diamond microwave plasma chemical vapor deposition(MPCVD) residual nitrogen

The growth temperatures dependence of optical and electrical properties of InN films

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Science China(Physics,Mechanics & Astronomy) 2008年第3期51卷 237-242页

作者： LIU Bin ZHANG Rong XIE ZiLi XIU XiangQian LI Liang KONG JieYing YU HuiQiang HAN Pin gu shulin SHI Yi ZHENG YouDou TANG Chenguang CHEN YongHai WANG Zhanguo Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and Department of Physics Nanjing UniversityNanjing 210093China Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

InN films grown on sapphire at different substrate temperatures from 550°C to 700°C by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100°C) was used as a buffer for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be improved by increasing the growth temperature to 600°C. Further high substrate temperatures may promote the thermal decomposition of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed to characterize the optical and electrical properties of InN films, which also indicates strong growth temperature dependence. The InN films grown at temperature of 600°C show not only a high mobility with low carrier concentration, but also a strong infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600°C, the Hall mobility achieves up to 938 cm2/Vs with electron concentration of 3.9 × 1018 cm?3.

关键词： metalorganic chemical vapor deposition X-ray diffraction photoluminescence

High performance lateral Schottky diodes based on quasi-degenerated Ga_2O_3

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Chinese Physics B 2019年第3期28卷 54-59页

作者： Yang Xu Xuanhu Chen Liang Cheng Fang-Fang Ren Jianjun Zhou Song Bai Hai Lu shulin gu Rong Zhang Youdou Zheng Jiandong Ye School of Electronic Science and Engineering Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics Nanjing UniversityNanjing 210093China Research Institute of Shenzhen Nanjing UniversityShenzhen 518057China State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices The 55th Research Institute of China Electronics Technology Group CorporationNanjing 210016China

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.

关键词： β-Ga2O3 Schottky diode transport mechanism quasi-degeneration rectifier

Hybrid plasmonic–dielectric metal-nanowire coupler for high-efficiency broadband nonlinear frequency conversion

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Photonics Research 2022年第10期10卷 2337-2342页

作者： KUI-YING NIE SONG LUO FANG-FANG REN XUANHU CHEN shulin gu ZHANGHAI CHEN RONG ZHANG JIANDONG YE School of Electronic Science and Engineering Nanjing UniversityNanjing 210023China College of Physics&Engineering Technology Minzu Normal University of XingyiXingyi 562400China Department of Physics Xiamen UniversityXiamen 361005China

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 ***,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 ***,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 *** two contributors remarkably enhance local fields and consequently support the strong broadband SHG outputs in this hybrid nanostructure by releasing stringent phase-matching *** proposed nanoscale nonlinear optical converter enables the manipulation of nonlinear light–matter interactions toward the development of on-chip nanophotonic systems.

关键词： dielectric nonlinear plasmon

Heteroepitaxial growth of thick α-Ga_2O_3 film on sapphire(0001)by MIST-CVD technique

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Journal of Semiconductors 2019年第1期40卷 81-85页

作者： Tongchuan Ma Xuanhu Chen Fangfang Ren Shunming Zhu shulin gu Rong Zhang Youdou Zheng Jiandong Ye Research Institute of Shenzhen and School of Electronics Science and Engineering Nanjing University

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, *** 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.

关键词： ultra-wide bandgap semiconductor chemical vapor deposition epitaxy gallium oxide