Atomic interdiffusion at Au-GaAs interfaces studied with Al interlayers

Abstract

We have used soft-x-ray photoemission spectroscopy at Au/GaAs interfaces to determine the movement of Au, Ga, and As atoms during the initial stages of Schottky-barrier formation. Studies of core-level features obtained with a range of photon energies between 80 and 250 eV indicate that, at room temperature, Au atoms first diffuse into GaAs, followed by the nonstoichiometric outdiffusion of Ga and As into Au overlayers. Thin Au overlayers on GaAs promote a spatial distribution of dissociated Ga and As which depends on the overlayer thickness. These microscopic phenomena result in a local charge redistribution which determines the electronic properties of the macroscopic Au/GaAs junction. We discuss the application of Al atoms at the intimate metal-semiconductor interface either as immobile markers to establish the absolute motion of interface species on an atomic scale or as indicators of the overall interface motion.