Improved preparation techniques for preparing high-performance GaAs photocathodes.

Efficiency and lifetime are always problems raised with photocathodes during operation. With the purpose of obtaining high-performance GaAs photocathodes with high sensitivity and long operational lifetime, it is necessary to investigate the preparation techniques during both the cleaning and the activation procedure. By comparison with the classical preparation techniques, the improved preparation techniques with an optimized chemical etching method and activation procedure are proposed. The experimental results show that the optimized chemical etching solution is more effective in removing oxide and carbon contamination, which can help photocathodes obtain higher sensitivity. On this basis, better long wavelength response and longer operational lifetime can be obtained with the help of the more competitive activation procedure. The proposed preparation techniques will be useful for applications as a source of spin-polarized electrons.