Effect of annealing time on the adsorption of cesium atoms

The gallium arsenide (GaAs) photocathode generally requires a high temperature thermal cleaning before (Cs, O) activation in order to obtain an atomic level clean surface. The process is useful to adsorb and deposit cesium and oxygen atoms. Generally considered, the photocathode needs to be cooled to 60℃ to activate for achieving better results. People usually keep the annealing time for at least 1.5 hours in practical production. In order to explore the effect of annealing time on cesium atoms which were adsorbed on GaAs photocathode, the experiment monitored the activation curves of three GaAs photocathodes samples which annealed for 0.5 hour, 1.0 hour, 1.5 hours respectively, and then compared the occurrence moment of the photocurrent and the first cesium peak by different annealing waiting time. The difference of the activation curves reflects indirectly that the photocathode surface temperature had an influence on the adsorption of cesium atoms during activation process. This phenomenon could explain from two aspects about atoms adsorption and electronic transport. The work has referential significance for experimental research and industrial production.