Atom profiles of interfaces with polar-angle-dependent photoemission: Au/GaAs(100)

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Abstract
We present atom distribution profiles, obtained using nondestructive, polar-angle-dependent x-ray photoemission, of Au/GaAs(100)-c(8×2) interfaces formed at room temperature. The results confirm substrate disruption, the release of Ga and As atoms into the overlayer, and the presence of significant amounts of Ga and As atoms segregated near the vacuum surface. At high Au coverages, our analysis determines the number of segregated Ga and As atoms, shows that the distribution of these atoms decreases exponentially into the Au film (1/e length of ∼3 Å) and diminishes with increasing Au thickness, and finds that the solid solubility in the film is 0.2±0.1 at. % for both Ga and As. The heterogeneous profile indicates that the Au/GaAs reaction at the buried interface is very limited and that intermixing in the overlayer is dictated primarily by solubilities.