Photoemission studies of the effect of temperature on the Au–GaAs(110) interface

Abstract

We have performed soft x-ray photoemission spectroscopy (SXPS) measurements, using synchrotron radiation as the excitation source, to study cleaved n-type GaAs(110) surfaces covered with Au overlayers ranging in thickness from 0.3 monolayer (ML) to 80 ML. At room temperature our results show both band-bending effects and significant Au intermixing, with a continuous, monotonic shift of the Au 4f core levels toward their bulk positions with increasing Au coverage. Observation of the Ga 3d and As 3d core levels indicates a preferential As segregation to the surface at the highest Au coverages. The effect of heating (up to 500 °C) on a relatively thick (15 ML) Au overlayer has been studied using valence band as well as core level emission. These results indicate an increase in the Ga and As concentrations with evidence of metallic Ga formation. These findings have an important bearing on our understanding of Schottky barrier formation as well as the particular behavior of the Au–GaAs interface.