Photoionization in GaAs Photoconductive Semiconductor Switches

Abstract

The density distribution characteristics of non-equilibrium carrier from spontaneous emission ahead of the tip of the current filaments in high gain semi-insulating GaAs photoconductive semiconductor switches are analyzed. The results show that the ratio of volume to area of the current filament and the average carrier density in the current filaments are two key factors that affect the photoionization effects of the current filaments. The reabsorption of wavelengths λ ≤ 876 nm radiations plays a dominant role in producing the maximum carrier density. The maximum density of photo-generated carrier is approximately 1~3 orders of magnitude lower than the average density of excess carrier inside the current filaments.