The variation of spectral response of transmission-type GaAs photocathode in the seal process

Transmission-type GaAs photocathode are emerging from the laboratory as practical photo-sensing devices with vastly improved sensitivity and spectral range compared with other photocathode. It is widely used in the many fields such as semiconductor device, optical radiation measurement, camera device and low-level-light night vision. Measurement of parameters of photocathode, especially its spectral response, is of great importance on the technique of photocathode's performance. During the fabrication of photocathode, the technology of online spectral response measurement enables us to determine spectral response quickly and accurately. Through analyzing and comparing those measured response curves, much information about photocathodes, for example, the sensitivity, the photo-electron surface escape probability, the thickness of the active layer, the diffusion length of electrons and the back interface recombination velocity of electrons can be obtained which is useful in both the research and the fabrication of photocathodes (Zhiyuan Zhong and BenKang Chang, 1998; Andre et al, 1981).