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New photoemission measurements show higher Schottky barrier heights (≳1.3 eV) on atomically clean GaAs(110) surfaces at a Au coverage of about 25 monolayers. It is suggested that this effect is due to the movement of Au into the semiconductor; at room temperature it creates acceptor states near the valence band maximum (VBM) that cause the Fermi level at the surface (Efs ) to move close to the VBM. We found that heating of the GaAs(110) surface (above 100 °C) covered with a small amount of Au (0.2 monolayer) causes Efs to move back to its original position (on the clean surface before Au deposition). The heating process is found to greatly inhibit the formation of large barrier heights due to the removal of defect states from the surface region.

We report new photoemission studies of the Au-InP (110) interface for both n-andp-type samples using synchrotron radiation in the energy range 80 tol8S eV. By slowly increasing Au coverages and by studying core level structures and valence band spectra we have been able to differentiate between two coverage intervals. The lower coverage interval (8 < I ML) is dominated by band bending with no measurable chemical changes and with a total measured Schottky barrier height of 0.6 eV. In the higher coverage interval (I < 8<,37 ML), we observed changes in the In 4d and P 2p core level shapes and a monotonic shift of the Au 4/ to lower binding energies with increased Au coverage. Evidence of intermixing of Au with the P and In atoms indicates the formation of a nonabrupt interface. These results are at variance with the view that Au is a nonreactive metal on InP (110).