Experimental and theoretical research on heat cleaning process of GaAlAs photocathodes

During the heat cleaning process of GaAlAs photocathodes, Ga2O3 and Al2O3 occur through chemical reaction. Adsorption models with Ga2O3 and Al2O3 on Ga0.5Al0.5As(001)beta(2) (2 x 4) phase are built and calculated through first-principles method. A heat cleaning experiment is performed. Combining the experimental and calculation results, heating temperature and chemical reactions at the surface are analyzed. Work function, electron transfer and dipole moment are analyzed, the reason why quantum efficiency of GaAlAs photocathodes are much lower than that of GaAs photocathodes is analyzed. Additionally, band structure and DOS curves are compared. (C) 2018 Elsevier GmbH. All rights reserved.