The Cs3Sb photocathode is an old topic in photo gun application, because it has high quantum efficiency illuminated by visible light, which saves the cost of drive laser system.
Preprared with our current preparation system with 10-9 mbar vacuum environment, Cs3Sb photocathode reached 1.5% under UV laser after two cycles of Yo-yo process. SEM measurement was done to detect the film quality, which shows the Cs/Sb layer with the stoichiometric rate of 2.7 on the Mo sample. The substrate was completely covered with homogeneous film. On the film some islands with the size of µm level are observed, which response actually the rich distribution of cesium.