COMPUTER SIMULATION OF HIGH-GAIN GaAs PHOTOCONDUCTIVESEMICONDUCTOR SWITCHES

Photoconductive switches are one of the few devices that allow the generation of high-voltage electrical pulses with sub-nanosecond rise time. They have a lot of special characters and then can be widely used in ultrahigh velocity theory , high power pulse generation and the other fields. So it is necessary to study their principles.In this paper two modes of high-gain GaAs photoconductive semiconductor switch , i.e. the linear mode and the nonlinear one are studied.Aiming at the linear mode , Maxwell curl equations , including the conductive current components , are solved using a Finite-Difference Time-Domain scheme.As to the nonlinear mode , a Monte Carlo simulation method is developed to characterize the transition in high-gain GaAs photoconductive semiconductor switch . The results indicate that the lock-on effect originates from the electrons rransfering from the P valley to the X valley.