非线性光电导开关载流子碰撞电离分析

对非线性GaAs光电导开关在锁定期间的电流成丝现象、具有负微分迁移率的速场特性、深能级的陷阱效应、光子的再吸收等因素进行分析,建立了非线性光电导开关锁定期间的连续性方程和电中性方程.基于该方程组,用有限差分法计算了偏压为2 200 V的3.5 mm GaAs∶EL2非线性光电导开关的电流实验数据,得到电流丝内载流子瞬态特性为：载流子浓度约为1017 cm－3,EL2电子陷阱近似饱和；电子电流随锁定时间明显下降,空穴电流基本不变；单位寿命时间载流子雪崩倍增因子的均值约为1.2,其统计起伏随锁定时间增大.

Analysis of Carrier Impact Ionization in Nonlinear Photoconductive Semiconductor Switch

The continuity equation and electric-charge balance equation of nonlinear GaAs photoconductive semiconductor switches (PCSS) in Lock-on state were established,in which the current filaments,the velocity-electrical field characteristic with negative differential mobility,the deep level traps and the reabsorption of photons from carrier combination were considered.Based on the equations and the experimental data of 3.5 mm GaAs∶EL2 PCSS which was biased at 2 200 V and in the nonlinear work mode,by the finite difference calculation,the following conclusions on the transient characteristics of carriers within the current filaments were drawn:1)The concentration of current carriers is about 1017 cm－3,and the EL2 electron traps are almost saturated.2)The electron current obviously falls down with the lock-on time but the hole current nearly keep a constant.3)The carrier avalanche multiplication factor is averagely 1.2 in one carrier lifetime and the statistical fluctuation increases with the Lock-on time.