Comparative research for transmission-mode GaAs photocathodes of different doping structures on surface photovoltage

In order to well study the internal body performance for transmission-mode GaAs photocathode of different varied doping structures, two GaAs photocathodes of exponential doping structure and gradient doping structure were designed respectively. Because surface photovoltage spectrum has close relation with the internal properties of GaAs photocathodes, the connection between surface photovoltage and internal electronic field was well discussed through deduction and calculation. The difference of two structures and the value of internal electronic energy were exactly calculated and verified by experiments. The internal band bending energy could form an internal electronic field with the same direction, which could help the photo-excited electrons to move toward surface barrier layer. This research shows a better method to well study the varied doping structures for GaAs photocathode materials and will help to improve the growth structure for transmission-mode GaAs photocathode module in the future.