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Chinese Physics B 2016年第1期25卷 796-801页

作者：张雅超周小伟许晟瑞陈大正王之哲汪星张金风张进成郝跃 State Key Discipline laboratory of Wide band Gap Semiconductor Technology School of Microelectronics Xidian University

Pulsed metal organic chemical vapor deposition is introduced into the growth of InGaN channel heterostructure for improving material qualities and transport properties. High-resolution transmission electron microscopy imaging shows the phase separation free InGaN channel with smooth and abrupt interface. A very high two-dimensional electron gas density of approximately 1.85 x 10^13 cm-2 is obtained due to the superior carrier confinement. In addition, the Hall mobility reaches 967 cruZ/V-s, owing to the suppression of interface roughness scattering. Furthermore, temperature-dependent Hall measurement results show that InGaN channel heterostructure possesses a steady two-dimensional electron gas density over the tested temperature range, and has superior transport properties at elevated temperatures compared with the traditional GaN channel heterostructure. The gratifying results imply that InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition is a promising candidate for microwave power devices.

关键词： heterostructure InGaN channel pulsed metal organic chemical vapor deposition

First-principle calculation on the defect energy level of carbon vacancy in 4H-SiC

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Chinese Physics B 2010年第10期19卷 436-440页

作者：贾仁需张玉明张义门 School of Microelectronics Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices Xidian University

First, electronic structures of perfect wurtzite 4H-SiC were calculated by using first-principle ultra-soft pseudopotential approach of the plane wave based on the density functional theory; and the structure changes, band structures, and density of states were studied. Then the defect energy level of carbon vacancy in band gap was examined by substituting the carbon in 4H-SiC with carbon vacancy. The calculated results indicate the new defect energy level generated by the carbon vacancy, and its location in the band gap in 4H-SiC, which has the character of deep acceptor. A proper explanation for green luminescence in 4H-SiC is given according to the calculated results which are in good agreement with our measurement results.

关键词： 4H-SiC energy band structure carbon vacancy

Growth of InGaN and double heterojunction structure with InGaN back barrier

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Journal of Semiconductors 2010年第12期31卷 16-19页

作者：史林玉张进城王昊薛军帅欧新秀付小凡陈珂郝跃 Key laboratory of Wide band Gap Semiconductor Materials and Devices Institutes of MicroelectronicsXidian University

We study the growth of an InGaN and A1GaN/GaN/InGaN/GaN double heterojunction structure by metal organic chemical vapor deposition （MOCVD）. It is found that the crystal quality of the InGaN back barrier layer significantly affects the electronic property of the A1GaN/GaN/InGaN/GaN double heterojunction. A high crystal quality InGaN layer is obtained by optimizing the growth pressure and temperature. Due to the InGaN layer polarization field opposite to that in the A1GaN layer, an additional potential barrier is formed between the GaN and the InGaN layer, which enhances carrier confinement of the 2DEG and reduces the buffer leakage current of devices. The double het- erojunetion high-electron-mobility transistors with an InGaN back barrier yield a drain induced barrier lowering of 1.5 mV/V and the off-sate source-drain leakage current is as low as 2.6μA/mm at VDS = 10 V.

关键词： InGaN back barrier double hererojunction carrier confinement

Al/Ti/4H-SiC Schottky barrier diodes with inhomogeneous barrier heights

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Chinese Physics B 2011年第8期20卷 384-388页

作者：王悦湖张义门张玉明宋庆文贾仁需 School of Microelectronics and Key laboratory of Wide band-Gap Semiconductor Materials and Devices Xidian University

This paper investigates the current-voltage （I-V） characteristics of Al/Ti/4H-SiC Schottky barrier diodes （SBDs） in the temperature range of 77 K-500 K, which shows that Al/Ti/4H SiC SBDs have good rectifying behaviour. An abnormal behaviour, in which the zero bias barrier height decreases while the ideality factor increases with decreasing temperature （T）, has been successfully interpreted by using thermionic emission theory with Gaussian distribution of the barrier heights due to the inhomogeneous barrier height at the A1/Ti/4H-SiC interface. The effective Richardson constant A＊ = 154 A/cm2 . K2 is determined by means of a modified Richardson plot In（I0/T2） - （qσ）2/2（κT）2 versus q/kT, which is very close to the theoretical value 146 A/cm2 · K2.

关键词： Schottky contact 4H-SiC barrier height inhomogeneity temperature

A 9.8-mW 1.2-GHz CMOS frequency synthesizer with a low phase-noise lC-VCO and an I/Q frequency divider

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Journal of Semiconductors 2011年第7期32卷 108-114页

作者：李振荣庄奕琪李兵靳刚 Key laboratory of the Ministry of Education for Wide band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

A 1.2 GHz frequency synthesizer integrated in a RF receiver for Beidou navigation is implemented in standard 0.18μm CMOS technology.A distributed biased varactor lC voltage-controlled oscillator is employed to achieve low tuning sensitivity and optimized phase noise performance.A high-speed and low-switching-noise divider-by-2 circuit based on a source-coupled logic structure is adopted to generate a quadrature（I/Q） local oscillating signal.A high-speed 8/9 dual-modulus prescaler（DMP）,a programmable-delay phase frequency detector without dead-zone problem,and a programmable-current charge pump are also integrated into the frequency synthesizer. The frequency synthesizer demonstrates an output frequency from 1.05 to 1.30 GHz,and the phase noise is-98.53 dBc/Hz at 100-kHz offset and -121.92 dBc/Hz at 1-MHz offset from the carrier frequency of 1.21 GHz. The power dissipation of the core circuits without the output buffer is 9.8 mW from a 1.8 V power *** total area of the receiver is 2.4×1.6 mm^2.

关键词： Beidou receiver frequency synthesizer voltage-controlled oscillator quadrature output divider phase noise

Hybrid solar cell based on polythiophene and GaN nanoparticles composite

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Chinese Physics B 2014年第2期23卷 604-608页

作者：冯倩时鹏李宇坤杜锴王强冯庆郝跃 School of Microelectronics Xidian University Key laboratory of Wide band-Gap Semiconductor Materials and Devices Xidian University

Hybrid solar cells based on poly（3-hexylthiophene）（P3HT） and Galium nitride （GaN） nanoparticle bulk heterojunc- tion are fabricated and analyzed. The GaN nanocrystal is synthesized by means of a combination of sol-gel process with high temperature ammoniation using Ga（OCzH5） as a precursor. Their characteristics are determined by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. With the addition of GaN nanoparticle to P3HT, the device performance is greatly enhanced.

关键词： gallium nitride nanocrystal hybrid solar cell P3HT

Electrical characteristics of SiGe-on-insulator nMOSFET and SiGe-silicon-on-aluminum nitride nMOSFET

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Chinese Physics B 2010年第12期19卷 472-477页

作者：刘红侠李斌李劲袁博郝跃 Key lab of Ministry of Education for Wide band-Gap Semiconductor Devices School of MicroelectronicsXidian University

This paper investigates the electrical characteristics and temperature distribution of strained Si/SiGe n-type metal oxide semiconductor field effect transistor （nMOSFET） fabricated on silicon-on-aluminum nitride （SOAN） substrate. This novel structure is named SGSOAN nMOSFET. A comparative study of self-heating effect of nMOSFET fabricated on SGOI and SGSOAN is presented. Numerical results show that this novel SGSOAN structure can greatly eliminate excessive self-heating in devices, which gives a more promising application for silicon on insulator to work at high temperatures.

关键词： electrical characteristics self-heating effect SiGe-on insulator SiGe-silicon-on-aluminum nitride

Influence of ^(60)Co gamma radiation on fluorine plasma treated enhancement-mode high-electron-mobility transistor

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Chinese Physics B 2011年第5期20卷 439-443页

作者：全思郝跃马晓华于惠游 Key laboratory of Wide band Gap Semiconductor Materials and Devices Institute of MicroelectronicsXidian University

A1GaN/GaN depletion-mode high-electron-mobility transistor （D-HEMT） and fluorine （F） plasma treated enhancement-mode high-electron-mobility transistor （E-HEMT） are exposed to 60Co gamma radiation with a dose of 1.6 Mrad （Si）. No degradation is observed in the performance of D-HEMT. However, the maximum transeonductance of E-HEMT is increased after radiation. The 2DEG density and the mobility are calculated from the results of capacitance-voltage measurement. The electron mobility decreases after fluorine plasma treatment and recovers after radiation. Conductance measurements in a frequency range from 10 kHz to 1 MHz are used to characterize the trapping effects in the devices. A new type of trap is observed in the F plasma treated E-HEMT compared with the D-HEMT, but the density of the trap decreases by radiation. Fitting of Gp/w data yields the trap densities DT = （1-3）Х1012 cm^-***^-1 and DT = （0,2-0.8）Х10^12 cm^2-eV^-1 before and after radiation, respectively. The time constant is 0.5 ms-6 ms. With F plasma treatment, the trap is introduced by etch damage and degrades the electronic mobility. After 60Co gamma radiation, the etch damage decreases and the electron mobility is improved. The gamma radiation can recover the etch damage caused by F plasma treatment.

关键词： A1GaN/GaN enhancement-mode high-electron-mobility transistors fluorine plasmatreatment 60Co gamma radiation

Degradation of ultra-thin gate oxide lDD NMOSFET under GIDl stress

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Journal of Semiconductors 2009年第4期30卷 34-37页

作者：胡仕刚郝跃曹艳荣马晓华吴笑峰陈炽周清军 Key laboratory of Wide band-Gap Semiconductor Materials and Devices School of Microelectronics Xidian University

The degradation of device under GIDl （gate-induced drain leakage current） stress has been studied using lDD NMOSFETs with 1.4 nm gate oxides. Experimental result shows that the degradation of device parameters depends more strongly on Vd than on Vg. The characteristics of the GIDl current are used to analyze the damage generated during the stress. It is clearly found that the change of GIDl current before and after stress can be divided into two stages. The trapping of holes in the oxide is dominant in the first stage, but that of electrons in the oxide is dominant in the second stage. It is due to the common effects of edge direct tunneling and band-to-band tunneling. SIlC（stress induced leakage current）in the NMOSFET decreases with increasing stress time under GIDl stress. The degradation characteristic of SIlC also shows saturating time dependence. SIlC is strongly dependent on the measured gate voltage. The higher the measured gate voltage, the less serious the degradation of the gate current. A likely mechanism is presented to explain the origin of SIlC during GIDl stress.

关键词： GIDl interface traps direct tunneling SIlC

Al0.30Ga0.70N/GaN/Al0.07Ga0.93N Double Heterostructure High Electron Mobility Transistors with a Record Saturation Drain Current of 1050 mA/mm

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Chinese Physics letters 2015年第11期32卷 110-113页

作者：李祥东张进成郭振兴江海清邹瑜张苇杭何云龙蒋仁渊赵胜雷郝跃 Key lab of Wide band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

We report Al0.30Ga0.70N//GaN/Al0.07Ga0.93N double heterostructure high electron mobility transistors with a record saturation drain current of 1050mA/mm. By optimizing the graded buffer layer and the GaN channel thickness, both the crystal quality and the device performance are improved signiflcantly, including electron mobility promoted from 1535 to 1602 cm2//V.s, sheet carrier density improved from 0.87× 10^13 to 1.15× 10^13 cm^-2, edge dislocation density reduced from 2.5× 10^10 to 1.3× 10^9 cm^ -2, saturation drain current promoted from 757 to record 1050mA/mm, mesa lealmge reduced by two orders in magnitude, and breakdown voltage promoted from 72 to 108 V.

关键词： GaN Ga N/GaN/Al