Abstract
Semi-insulating gallium arsenide (GaAs) photoconductive semiconductor switches (PCSS) have great potential for high voltage switching application, however, the utility is restricted by surface flashover which would result in breakdown. In this paper, a model of photo-activated charge wave was proposed based on the theory of photo-activated charge domain (PACD) in GaAs PCSS, and moderate suppression of PACD formation by loading the semiconductor surface with dielectric material was investigated theoretically and experimentally. Current as high as 3.7 kA was obtained at 28 kV, implying that this method can effectively inhibit the surface flashover and improve the service life of DC charged GaAs PCSS.