Comparative research on Cs/O activation source ratio for GaAs photocathodes

Through the comparative research on cathode material by surface photovoltage spectroscopy (SPS) before activation and spectral response current (SRC) after activation, the value of surface escape probability (SEP) can be well measured. By the experiments and calculations for the designed cathode material, the influence of Cs/O activation source ratio on SRC and SEP can be well fitted. The lower and excessive source ratio can not get well SEP value and only the appropriate source ratio can get the better SEP value. Through the analysis of surface barrier layer model, the influence of Cs/O source ratio on the formation of surface barrier layer were well discussed. The appropriate source ratio can help to form the best double dipole arrange structure and better depth of Cs–O layer. This comparative research method can help to well study and optimize the Cs/O activation technique and varied doping structure design for GaAs photocathodes in the future.