Performance stability of reflection-mode AlGaN photocathode under different preparation methods

摘要

To research the attenuation performance of the AlGaN photocathode, three samples with same structures grown by metalorganic chemical vapor deposition (MOCVD) were activated with three different activation methods, which are Cs-only, Cs-O and Cs-O-Cs activation, respectively. The spectral responses and attenuated photocurrents of three AlGaN photocathodes were measured, the result shows that the Cs-O activated AlGaN photocathode have the lowest attenuation speed in the first few hours, the next are Cs-O-Cs and Cs-only activation, respectively. After the Cs-O-Cs activation sample has attenuated 90 min, its attenuation photocurrent curve is coincident with the Cs-O activation sample in the next measurement. The main factor which affects the photocurrent attenuation is Cs atom desorbed from the photocathodes surface.