Influence of Al fraction on photoemission performance of AlGaN photocathode

摘要

To research the photoemission performance of a transmission-mode Al_(1-x)Ga_xN photocathode, Al_(0.24)Ga_(0.76)N and GaN photocathodes with the same structure were activated, their spectral responses were measured using a multi-information measurement system at room temperature, and the photocathode parameters were obtained by fitting quantum efficiency curves. The results showed that both the reflective-mode and transmission-mode spectral responses of the AlGaN photocathode were lower than those of the GaN photocathode. Compared with the GaN photocathode, the short-wavelength spectral response of the Al_(0.24)Ga_(0.76)N photocathode was less seriously affected by lattice defects between the buffer and emission layers. The Al atom at the AlGaN photocathode surface could affect the optimal Cs adsorption position, which mainly affects the surface electron escape probability of the photocathode.