Investigations of the charge limit phenomenon in GaAs photocathodes

The doping concentration dependence of the charge limit phenomenon is studied using a set of thin unstrained GaAs. The p-type doping concentration ranges from 5×1018 cm−3 to 5×1019 cm−3. The surface photovoltage effect on photoemission is found to diminish rapidly with increasing doping concentration. The doping concentration effect on electron polarization is studied using high surface doped strained GaAs. The charge enhancement is explored using a direct, lateral surface charge sink in the form of a metallic grid overlaid on the surface.