弱光触发下GaAs光电导开关的载流子输运和热失效机制  

Carrier Transport and Thermal Failure Mechanism of GaAs Photoconductive Semiconductor Switch at Low Optical Excitation

作　　者：司鑫阳 徐鸣[1] 王文豪 常家豪 王铖杰 Si Xinyang;Xu Ming;Wang Wenhao;Chang Jiahao;Wang Chengjie(Applied Physics Department Xi’an University of Technology,Xi’an 710048 China)

机构地区：[1]西安理工大学应用物理系,西安710048

出　　处：《电工技术学报》2024年第7期2153-2160,共8页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金项目(52277164,51877177);陕西高校青年创新团队项目(超快光电器件与材料);陕西省科技计划重点项目(2021JZ-48);陕西省教育厅青年创新团队建设项目(21JP085,21JP088,22JP058)资助。

摘　　要：弱光触发下高倍增砷化镓光电导开关(GaAs PCSS)内以丝状电流为表现形式的载流子输运机制对其瞬态工作特性和寿命研究有重要意义。该文基于有限元方法构建了GaAs PCSS的物理模型,结合丝状电流的生热机制对1.5μJ弱光触发下开关的瞬态输出电流和晶格温度进行了仿真分析,考察了偏置电场对GaAs PCSS输出特性的影响。通过不同时刻开关内部的瞬态电场、电子浓度和晶格温度等方面研究了高倍增模式下GaAs PCSS的光生载流子输运过程和损伤机理。结果表明,高密度丝状电流的存在伴随于高场畴的产生和发展。开关内部电场越高,负微分效应引起的载流子聚束现象越明显,相应的电子浓度和晶格温度值也越高;在浓度达1017 cm^(-3)数量级的等离子体通道中,阳极附近电场强度和晶格温度最大值分别为220 kV/cm和821.92 K。Gallium arsenide photoconductive semiconductor switch(GaAs PCSS)is one of the most promising solid-state switches with a simple structure,fast response time,low jitter,strong optical trigger isolation,and easy integration,which has a wide range of applications in terahertz technology,ultra-fast pulse sources,and high power microwave.GaAs PCSS has two operating modes:linear and high gain(HG).However,the conduction process of the HG GaAs PCSS is often accompanied by the high-density filamentary current under low optical energy(nJ-µJ),which generates a lot of Joule heat to damage device.In this paper,a two-dimensional(2D)electrothermal coupling model of GaAs PCSS is set up based on the self-heating effect,and the transient characteristics of the switch are investigated at the optical excitation of 1.5µJ.Firstly,the output currents of HG GaAs PCSS under different bias electric fields are investigated.The results show that the corresponding output current waveforms have obvious trailing(lock-on),and the locking currents are almost the same at the optical excitation of 1.5µJ as the bias electric field increases from 60 kV/cm to 78 kV/cm.In addition,the output current amplitude increases and the rise time decreases accordingly with the increase of the bias electric field.Secondly,the lattice temperatures of HG GaAs PCSS are investigated under different bias electric fields,considering the influence of the thermal field on the stability and physical process of the device.The results show that the rise of lattice temperature over time is divided into three stages combined with the current waveform,namely,the current rising stage,current descending stage and current lock-on stage.The rise rate of lattice temperature is determined by the bias electric field and the rise stage.The lattice temperature increases with the increase of the bias electric field,and the maximum lattice temperature can reach 821.92 K at the bias electric field of 78 kV/cm.Finally,the carrier transport process and thermal failure mechanism inside t

关 键 词：GAAS 光电导开关 高倍增模式 丝状电流 输运机制 

分 类 号：O473[理学—半导体物理] TM564[理学—物理]