CHEMICAL AND ELECTRONIC-PROPERTIES OF AL/[VICINAL GAAS(100)] AND AU/[VICINAL GAAS(100)] INTERFACE

Soft-x-ray photoemission studies of Al and Au on molecular-beam epitaxially grown GaAs(100) vicinal surfaces at low temperature demonstrate orientation-dependent interface electronic properties and chemistry. Misorientation of the substrate introduces both electrically and chemically active sites. With increasing misorientation-induced step-site density, the Fermi level at the Al/GaAs(100) interface moves toward the midgap. For the Au/GaAs(100) interface, substrate misorientation has only a minor effect on the electronic barrier height. The chemically active sites modify the extent of interface chemistry. A self-consistent electrostatic calculation of the misorientation-dependent barrier height for Al interfaces indicates a nearly one-to-one correlation between interface states and step-induced bonding sites. These results emphasize the importance of an atomic-scale interface bonding structure in the Schottky-barrier formation.