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Ge/Si heterojunction L-shape tunnel field-effect transistors with hetero-gate-dielectric

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Chinese Physics B 2018年第7期27卷 572-579页

作者： CongLi Zhi-Rui Yan Yi-Qi Zhuang Xiao-Long Zhao Jia-Min Guo wide bandgap semiconductor technology disciplines state key laboratory School of MicroelectronicsXidian UniversityXi＇an 710071China

A Ge/Si heterojunction L-shaped tunnel field-effect transistor combined with hetero-gate-dielectric （GHL-TFET） is proposed and investigated by TCAD simulation. Current-voltage characteristics, energy-band diagrams, and the distri- bution of the band-to-band tunneling （BTBT） generation rate of GHL-TFET are analyzed. In addition, the effect of the vertical channel width on the ON-current is studied and the thickness of the gate dielectric is optimized for better suppression of ambipolar current. Moreover, analog/RF figure-of-merits of GHL-TFET are also investigated in terms of the cut-off frequency and gain bandwidth production. Simulation results indicate that the ON-current of GHL-TFET is increased by about three orders of magnitude compared with that of the conventional L-shaped TFET. Besides, the introduction of the hetero-gate-dielectric not only suppresses the ambipolar current effectively but also improves the analog/RF performance drastically. It is demonstrated that the maximum cut-off frequency of GHL-TFET is about 160 GHz, which is 20 times higher than that of the conventional L-shaped TFET.

关键词： tunnel field-effect transistors Ge/Si heterojunction hetero-gate-dielectric ambipolar effect

Application of nano-patterned InGaN fabricated by selfassembled Ni nano-masks in green InGaN/GaN multiple quantum wells

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Journal of semiconductors 2023年第4期44卷 86-91页

作者： Ruoshi Peng Shengrui Xu Xiaomeng Fan Hongchang Tao Huake Su Yuan Gao Jincheng Zhang Yue Hao wide bandgap semiconductor technology disciplines state key laboratory School of MicroelectronicsXi'dian UniversityXi'an 710071China

The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells(MQWs)structure,to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN,as well as to enhance the light *** different self-assembled nano-masks were formed on InGaN by annealing thin Ni layers of different ***,the InGaN films were etched into nano-patterned *** with the green MQWs structure grown on untreated InGaN film,which on nano-patterned InGaN had better luminous *** them the MQWs performed best when 3 nm thick Ni film was used as mask,because that optimally balanced the effects of nano-patterned InGaN on the crystal quality and the light output.

关键词： GaN InGaN nano-mask nano-patterned MQWs

Theoretical prediction of new C–Si alloys in C2/m-20 structure

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Chinese Physics B 2017年第4期26卷 283-292页

作者：徐向阳柴常春樊庆扬杨银堂 state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian UniversityXi'an 710071China

We study structural,mechanical,and electronic properties of C_（20）,Si_（20） and their alloys（C_（16）Si_4,C_（12）Si_8,C_8Si_（12）,and C_4Si_（16）） in C2/m structure by using density functional theory（DFT） based on first-principles *** obtained elastic constants and the phonon spectra reveal mechanical and dynamic *** calculated formation enthalpy shows that the C-Si alloys might exist at a specified high temperature *** ratio of BIG and Poisson＇s ratio indicate that these C-Si alloys in C2/m-20 structure are all *** elastic anisotropic properties derived by bulk modulus and shear modulus show slight *** addition,the band structures and density of states are also depicted,which reveal that C_（20）,C_（16）Si_4,and Si_（20） are indirect band gap semiconductors,while C_8Si_（12） and C_4Si_（16） are semi-metallic ***,a direct band gap semiconductor（C_（12）Si_8） is obtained by doping two indirect band gap semiconductors（C_（20） and Si_（20））.

关键词： C–Si alloys mechanical properties band structure direct band gap semiconductor

Effects of notch structures on DC and RF performances of AlGaN/GaN high electron mobility transistors

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Chinese Physics B 2021年第4期30卷 166-172页

作者： Hao Zou Lin-An Yang Xiao-Hua Ma Yue Hao The state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian UniversityXi'an 710071China

The effects of various notch structures on direct current(DC) and radio frequency(RF) performances of AlGaN/GaN high electron mobility transistors(HEMTs) are *** AlGaN/GaN HEMTs,each with a 0.8-μm gate length,50-μm gate width,and 3-μm source-drain distance in various notch structures at the AlGaN/GaN barrier layer,are manufactured to achieve the desired DC and RF *** maximum drain current(I_(ds,max)),pinch-off voltage(V_(th)),maximum transconductance(gm),gate voltage swing(GVS),subthreshold current,gate leakage current,pulsed I-V characteristics,breakdown voltage,cut-off frequency(f_(T)),and maximum oscillation frequency(f_(max)) are *** results show that the double-notch structure HEMT has a 30% improvement of gate voltage swing,a 42.2% improvement of breakdown voltage,and a 9% improvement of cut-off frequency compared with the conventional *** notch structure also has a good suppression of the current collapse.

关键词： AlGaN/GaN high electron mobility transistors(HEMTs) barrier layer notch

Experimental demonstration of photonic spike-timing-dependent plasticity based on a VCSOA

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Science China(Information Sciences) 2022年第8期65卷 228-237页

作者： Ziwei SONG Shuiying XIANG Xingyu CAO Shihao ZHAO Yue HAO state key laboratory of Integrated Service Networks Xidian University state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian University

We experimentally design two photonic spike-timing-dependent plasticity(STDP) schemes based on a single vertical-cavity semiconductor optical amplifier(VCSOA) and demonstrate the photonic implementation of STDP characteristics. In the first scheme, a single-polarized optical pulse train is injected into the VCSOA, in which a pair of optical pulses with a time difference is designed to emulate the pre-synaptic and post-synaptic spikes. In the second scheme, dual-polarized optical pulses emulating the pre-synaptic and post-synaptic spikes are injected into the single VCSOA. Furthermore, the effects of the initial wavelength detuning and the power of the input optical pulse on the STDP curve are analyzed. The proposed photonic STDP schemes based on a single VCSOA need relatively low bias current and power consumption, and thus,are ideal optical synaptic devices forming key components in the construction of the photonic neuromorphic computing system.

关键词： neuromorphic photonics vertical-cavity semiconductor optical amplifier spike-timing-dependent plasticity optical neural systems pulsed optical injection

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Performance improvement of β-Ga2O3 SBD-based rectifier with embedded microchannels in ceramic substrate

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Science China(Information Sciences) 2024年第5期67卷 341-342页

作者： Wen HONG Chao ZHANG Fang ZHANG Xuefeng ZHENG Xiaohua MA Yue HAO state key laboratory of wide-bandgap semiconductor Devices and Integrated technology School of MicroelectronicsXidian University

With the development of integrated circuits, there is a growing demand for higher power devices [1]. Gallium oxide（Ga2O3） holds promise for high power devices due to its wide bandgap and high breakdown electric field strength [2].However, its low thermal conductivity induces severe selfheating effects, limiting its performance and ***, effective thermal management techniques are urgently needed for Ga2O3devices.

关键词： Gallium compounds

A modified supervised learning rule for training a photonic spiking neural network to recognize digital patterns

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Science China(Information Sciences) 2021年第2期64卷 202-210页

作者： Yahui ZHANG Shuiying XIANG Xingxing GUO Aijun WEN Yue HAO state key laboratory of Integrated Service Networks Xidian University state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian University

A modified supervised learning rule which is suitable for training photonic spiking neural networks(SNN) is proposed for the first time. The proposed learning rule is independent of the time intervals between actual spike and desired spike or between presynaptic spike and postsynaptic spike. Based on the proposed supervised learning rule, 10 digital images are learned in photonic neural network which consists of 30 presynaptic neurons and 10 postsynaptic neurons. Presynaptic and postsynaptic neurons are photonic neurons based on vertical-cavity surface-emitting lasers with an embedded saturable absorber(VCSEL-SA).The results show that 10 digital images are recognized correctly in photonic SNN after enough ***, the effects of learning rate, the jitters of learning rate, initial weights distribution of SNN and bias current of postsynaptic neurons(VCSELs-SA) on the recognized error are examined carefully based on the proposed learning rule. To the best of our knowledge, such modified supervised learning rule has not yet been reported, which would contribute to training photonic neural networks, and hence is interesting for neuromorphic photonic systems and pattern recognition.

关键词： vertical-cavity surface-emitting laser modified supervised learning rule optical spiking neural networks learning system pattern recognition

Experimental and numerical demonstration of hierarchical time-delay reservoir computing based on cascaded VCSELs with feedback and multiple injections

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Science China(Information Sciences) 2024年第2期67卷 279-290页

作者： Xingxing GUO Shuiying XIANG Xingyu CAO Biling GU state key laboratory of Integrated Service Networks Xidian University state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian University

In this paper, we propose and demonstrate experimentally and numerically a hierarchical timedelay optical reservoir computing(RC) system based on cascaded vertical-cavity surface-emitting lasers(VCSELs) with feedback and multiple injections. The prediction performance characteristics of the hierarchical time-delay RC system based on cascaded VCSELs under different reservoir layers are ***, the prediction performance of the hierarchical time-delay RC system is first improved and saturates as the number of reservoir layers increases. Besides, the impacts of key factors on predicting the hierarchical time-delay RC system are also analyzed in detail experimentally and numerically. This proposed hierarchical time-delay RC system based on VCSELs is useful for the further development of RC systems and may be beneficial to improve the ability of RC systems to solve more complex problems.

关键词： vertical-cavity surface-emitting laser reservoir computing neuromorphic photonics time-delay system information processing

Real-time optical spike-timing dependent plasticity in a single VCSEL with dual-polarized pulsed optical injection

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Science China(Information Sciences) 2020年第6期63卷 143-154页

作者： Shuiying XIANG Yanan HAN Xingxing GUO Aijun WEN Genquan HAN Yue HAO state key laboratory of Integrated Service Networks Xidian University state key Discipline laboratory of wide bandgap semiconductor technology School of MicroelectronicsXidian University

We propose and numerically realize an optical spike-timing dependent plasticity(STDP) scheme by using a single vertical-cavity surface-emitting laser(VCSEL). In the scheme, the VCSEL is subjected to an orthogonally-polarized continuous-wave optical injection(OPCWOI) and dual-polarized pulsed optical injections(DPPOI). Based on the widely used spin-flip model, the response spiking dynamics of VCSEL is numerically studied, and then the optical STDP in a single VCSEL is explored. The roles of bias current, the strength of OPCWOI and DPPOI, and the frequency detuning on the optical STDP curve are numerically analyzed. It is found that, by simultaneously utilizing the response spiking dynamics in two orthogonal polarization modes, an optical STDP could be achieved by using a single VCSEL. Furthermore, the weight update of STDP curve can be calculated in real-time. Additionally, the STDP curves can also be controlled by adjusting some controllable parameters. The real-time optical STDP based on a single VCSEL is numerically realized for the first time, which paves the way towards fully VCSELs-based photonic neuromorphic systems with low power consumption.

关键词： vertical-cavity surface-emitting laser optical spike-timing dependent plasticity neuromorphic photonic system dual polarized pulsed optical injections artificial intelligent systems