Orientation-dependent chemistry and Schottky-barrier formation at metal-GaAs interfaces

Soft-x-ray photoemission spectroscopy of metals deposited on GaAs demonstrates that minor misorientations of the (100) surface produce major deviations from Schottky-like behavior via increased chemical interactions. The degree of chemical activity correlates with the density of dangling bonds at the [110], [111]A, and (111)B steps, producing deep levels with acceptor character which dramatically reduce the range of Fermi-level stabilization. These results demonstrate the central role of local atomic bonding in the Schottky-barrier formation.