High Schottky barriers on and thermally induced processes at the Au-- GaAs(110) interface

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 (E/sub f/s ) to move close to the VBM. We found that heating of the GaAs(110) surface (above 100 0C) covered with a small amount of Au (0.2 monolayer) causes E/sub f/s 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