Surface photovoltage effects in photoemission from metal-GaP(110) interfaces: Importance for band bending evaluation

Photoelectron spectra from metal overlayers on GaP(110) show that the photoionization light source may induce a surface photovoltage, causing an energy shift of valence- and core-level peaks. We analyze the dependence of this surface photovoltage on metal coverage, substrate doping, and temperature. The presence of a surface photovoltage seriously affects the determination of surface band bending by photoelectron spectroscopy, a technique which is generally thought to reflect the equilibrium electronic structure of metal-semiconductor interfaces.