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Effect of a Single Threading Dislocation on Electrical and Single Photon Detection Characteristics of 4H-SiC Ultraviolet Avalanche Photodiodes

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Chinese Physics Letters 2020年第6期37卷 119-122页

作者： Lin-Lin Su Dong Zhou Qing Liu Fang-Fang Ren Dun-Jun Chen Rong Zhang you-dou zheng Hai Lu School of Electronic Science and Engineering Nanjing UniversityNanjing 210023China

We fabricated 4H-SiC ultraviolet avalanche photodiode(APD)arrays and systematically investigated the effect of threading dislocations on electrical and single photon detection characteristics of 4H-SiC *** on a statistical correlation study of individual device performance and structural defect mapping revealed by molten KOH etching,it is determined with high confidence level that even a single threading dislocation within APD active region would lead to apparent device performance degradation,including increase of dark current near breakdown voltage,premature breakdown and reduction of single photon detection efficiency at fixed dark count rate.

关键词： breakdown ultraviolet apparent

Transition of photoconductive and photovoltaic operation modes in amorphous Ga_2O_3-based solar-blind detectors tuned by oxygen vacancies

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Chinese Physics B 2019年第2期28卷 71-76页

作者： Yan-Fang Zhang Xuan-Hu Chen Yang Xu Fang-Fang Ren Shu-Lin Gu Rong Zhang you-dou zheng Jian-Dong Ye Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering Nanjing University Wuxi Institute of Technology Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics Nanjing University

We report on the transition of photovoltaic and photoconductive operation modes of the amorphous Ga_2O_3-based solar-blind photodetectors in metal–semiconductor–metal(MSM) configurations. The conversion from Ohmic to Schottky contacts at Ti/Ga_2O_3 interface is realized by tuning the conductivity of amorphous Ga_2O_3 films with delicate control of oxygen flux in the sputtering process. The abundant donor-like oxygen vacancies distributed near the Ti/Ga_2O_3 interface fascinate the tunneling process across the barrier and result in the formation of Ohmic contacts. As a consequence, the serious sub-gap absorption and persistent photoconductivity(PPC) effect degrades the performance of the photoconductive detectors. In contrast, the photovoltaic device with a Schottky contact exhibits an ultra-low dark current less than 1 pA,a high detectivity of 9.82×10^(12) cm·Hz^(1/2)·W^(-1), a fast response time of 243.9 μs, and a high ultraviolet C(UVC)-toultraviolet A(UVA) rejection ratio of 103. The promoting performance is attributed primarily to the reduction of the subgap states and the resultant suppression of PPC effect. With simple architecture, low fabrication cost, and easy fusion with modern high-speed integrated circuitry, these results provide a cost-effective way to realize high performance solar-blind photodetectors towards versatile practical applications.

关键词： amorphous gallium oxide solar-blind photodetector photovoltaic photoconductive

Negative transconductance effect in p-GaN gate AlGaN/GaN HEMTs by traps in unintentionally doped GaN buffer layer

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Chinese Physics B 2019年第10期28卷 504-509页

作者： Mei Ge Qing Cai Bao-Hua Zhang Dun-Jun Chen Li-Qun Hu Jun-Jun Xue Hai Lu Rong Zhang you-dou zheng The Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and EngineeringNanjing UniversityNanjing 210093China Department of Physics Changji CollegeChangji 831100China School of Electronic Science and Engineering Nanjing University of Posts and TelecommunicationsNanjing 210023China

We investigate the negative transconductance effect in p-GaN gate AlGaN/GaN high-electron-mobility transistor(HEMT) associated with traps in the unintentionally doped GaN buffer layer. We find that a negative transconductance effect occurs with increasing the trap concentration and capture cross section when calculating transfer *** electron tunneling through AlGaN barrier and the reduced electric field discrepancy between drain side and gate side induced by traps are reasonably explained by analyzing the band diagrams, output characteristics, and the electric field strength of the channel of the devices under different trap concentrations and capture cross sections.

关键词： AlGaN/GaN high-electron-mobility transistors(HEMTs) traps negative transconductance

Growth of β-Ga_2O_3 Films on Sapphire by Hydride Vapor Phase Epitaxy

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Chinese Physics Letters 2018年第5期35卷 141-143页

作者： Ze-Ning XIONG Xiang-Qian XIU Yue-Wen LI Xue-Mei HUA Zi-Li XIE Peng CHEN Bin LIU Ping HAN Rong ZHANG you-dou zheng Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and EngineeringNanjing University

Two-inch Ga_2O_3 films with（ˉ201）-orientation are grown on c-sapphire at 850–1050°C by hydride vapor phase epitaxy. High-resolution x-ray diffraction shows that pure β-Ga_2O_3 with a smooth surface has a higher crystal quality, and the Raman spectra reveal a very small residual strain in β-Ga_2O_3 grown by hydride vapor phase epitaxy compared with bulk single crystal. The optical transmittance is higher than 80% in the visible and near-UV regions, and the optical bandgap energy is calculated to be 4.9 e V.

关键词： Growth of Ga2O3 Films on Sapphire by Hydride Vapor Phase Epitaxy XRD

Comparison study of GaN films grown on porous and planar GaN templates

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Chinese Physics B 2020年第3期29卷 433-435页

作者： Shan Ding Yue-Wen Li Xiang-Qian Xiu Xue-Mei Hua Zi-Li Xie Tao Tao Peng Chen Bin Liu Rong Zhang you-dou zheng Key Laboratory of Advanced Photonic&Electronic Materials School of Electronic Science&EngineeringNanjing UniversityNanjing 210093China

The GaN thick films have been grown on porous GaN template and planar metal-organic chemical vapor deposition(MOCVD)-GaN template by halide vapor phase epitaxy(HVPE). The analysis results indicated that the GaN films grown on porous and planar GaN templates under the same growth conditions have similar structural, optical, and electrical properties. But the porous GaN templates could significantly reduce the stress in the HVPE-GaN epilayer and enhance the photoluminescence(PL) intensity. The voids in the porous template were critical for the strain relaxation in the GaN films and the increase of the PL intensity. Thus, the porous GaN converted from β-Ga2O3 film as a novel promising template is suitable for the growth of stress-free GaN films.

关键词： GaN porous template stress

Diamond-based electron emission:Structure,properties and mechanisms

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Chinese Physics B 2024年第9期33卷 165-177页

作者： Liang-Xue Gu Kai Yang Yan Teng Wei-Kang Zhao Geng-you Zhao Kang-Kang Fan Bo Feng Rong Zhang you-dou zheng Jian-Dong Ye Shun-Ming Zhu Kun Tang Shu-Lin Gu School of Electronic Science and Engineering Nanjing UniversityNanjing 210046China

Diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,*** with a hydrogen-terminated(H-terminated)surface has a negative electron affinity(NEA)and can easily produce surface electrons from valence or trapped electrons via optical absorption,thermal heating energy or carrier transport in a PN *** NEA of the H-terminated surface enables surface electrons to emit with high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting *** article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA *** electron emission is induced by different physical *** advancements in electron-emitting devices based on diamond are also ***,the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electronemitting devices.

关键词： diamond negative electron affinity(NEA) PN junction electron emission

Fabrication and Characterization of GaN-Based Micro-LEDs on Silicon Substrate

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Chinese Physics Letters 2019年第8期36卷 94-97页

作者： Qi Wang Jun-Chi Yu Tao Tao Bin Liu Ting Zhi Xu Cen Zi-Li Xie Xiang-Qian Xiu Yu-Gang Zhou you-dou zheng Rong Zhang Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and EngineeringNanjing UniversityNanjing210093 Nanjing National Laboratory of Microstructures Nanjing UniversityNanjing210093 College of Electronic and Optical Engineering&College of Microelectronics Nanjing University of Posts andTelecommunicationsNanjing210093

GaN-based micro light emitting diodes(micro-LEDs) on silicon(Si)substrates with 40μm in diameter are developed utilizing standard photolithography and inductively coupled plasma etching *** currentvoltage curves,the relatively low turn-on voltage of 2.8 V and low reverse leakage current in the order of 10-8 A/cm2 indicate good electrical *** the injection current increases,the electroluminescence emission wavelength hardly shifts at around 433 nm, and the relative external quantum efficiency slightly decays,because the impact of quantum-confined Stark effect is not serious in violet-blue *** GaN-LEDs are cost effective on large-area Si and suitable for substrate transfer or vertical device structures,the fabricated micro-LEDs on Si should have promising applications in the fields of high-resolution display and optical communication.

关键词： Fabrication Characterization Silicon

Synthesis and characterization of β-Ga_2O_3@GaN nanowires

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Chinese Physics B 2019年第2期28卷 445-448页

作者： Shuang Wang Yue-Wen Li Xiang-Qian Xiu Li-Ying Zhang Xue-Mei Hua Zi-Li Xie Tao Tao Bin Liu Peng Chen Rong Zhang you-dou zheng Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and EngineeringNanjing University

In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The effect of the oxidation temperature and time on the oxidation degree of GaN NWs was investigated systematically. The oxidation rate of GaN NWs was estimated at different temperatures.

关键词： β-Ga2O3@GaN nanowires thermal oxidation

Effect of oxygen on regulation of properties of moderately boron-doped diamond films

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Chinese Physics B 2022年第12期31卷 591-597页

作者： Dong-Yang Liu Li-Cai Hao Wei-Kang Zhao Zi-Ang Chen Kun Tang Shun-Ming Zhu Jian-Dong Ye Rong Zhang you-dou zheng Shu-Lin Gu School of Electronic Science and Engineering Nanjing UniversityNanjing 210093China The Shanghai Huahong Grace Semiconductor Manufacturing Corporation Shanghai 201203China Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics Nanjing UniversityNanjing 210093China

Regulation of oxygen on properties of moderately boron-doped diamond films is fully *** show that,with adding a small amount of oxygen(oxygen-to-carbon ratio<5.0%),the crystal quality of diamond is improved,and a suppression effect of residual nitrogen is *** increasing ratio of O/C from 2.5%to 20.0%,the hole concentration is firstly increased then *** change of hole concentration is also ***,the results of Hall effect measurement with temperatures from 300 K to 825 K show that,with adding a small amount of oxygen,boron and oxygen complex structures(especially B_(3)O and B_(4)O)are formed and exhibit as shallow donor in diamond,which results in increase of donor *** further increase of ratio of O/C,the inhibitory behaviors of oxygen on boron leads to decrease of acceptor concentration(the optical emission spectroscopy has shown that it is decreased with ratio of O/C more than 10.0%).This work demonstrates that oxygen-doping induced increasement of the crystalline and surface quality could be restored by the co-doping with *** technique could achieve boron-doped diamond films with both high quality and acceptable hole concentration,which is applicable to electronic level of usage.

关键词： moderately boron doped diamond crystal quality suppression effect boron and oxygen complex structures