Photo-induced change of the semiconductor–vacuum interface of p-GaAs(100) studied by photoelectron spectroscopy

The photo-induced change in the semiconductor–vacuum interface on GaAs(100) and Cs/GaAs(100) has been investigated with core-level photoelectron spectroscopy using synchrotron radiation and a mode-locked Nd:YAG laser. Both Ga-3d and As-3d photoelectron peaks showed transient energy shifts under the laser irradiation without any spectral change. The amounts of energy shift were strongly dependent on the sample temperature and laser photon flux. It is shown that the experimental results can be fitted to a theoretical curve which was derived from the photo-induced band bending scheme in the surface layer of the semiconductor.