Cesium and oxygen activated amorphous silicon germanium photocathodes for photo injectors

摘要

Amorphous silicon and amorphous silicon germanium photoemitters grown via radio frequency plasma enhanced chemical vapor deposition have been investigated to determine their usefulness as photoinjector electron sources. Characterized properties include activation process, wavelength dependent photoyield, germanium induced photoyield shift, background gas and ion sensitivities, and average transverse emission energy. While overall lower in yield than the GaAs photoemitter, many of their properties are comparable. The amorphous silicon photoemitter robustness upon gas and ion exposure is superior to that of GaAs. The combined properties of amorphous silicon germanium photoemitters make them ideal candidates for low cost photoinjector sources or as protective photoemitting layers on more sensitive photogenerating materials.