Interface chemistry and band bending induced by Pt deposition onto GaP(110)

The Pt/GaP(110) interface has been studied by core and valence level photoemission using synchrotron radiation. The results are characteristic of a reactive interface, where the GaP substrate is disrupted by the deposited platinum layer resulting in an increasing reacted Ga emission and a strong attenuation of the substrate Ga emission. The detailed analysis of band bending shows that Pt, being a high work-function material, nevertheless has a final pinning position which is close to that of other materials. The value for the Schottky barrier inferred from the photoemission data, Φbn is 1.56 eV. We observe a distortion of the equilibrium band arrangement by the incident photons, giving rise to a surface photovoltage even at room temperature. This effect can strongly influence the determination of surface band bending.