Electronic and Atomic Structure of GaAs Epitaxial Overlays on Si(111)

The atomic structure occurring at the interface between Si(111) and thin GaAs epitaxial overlayers has a pronounced effect on the surface electronic structure, thus making it possible to infer structural information by comparing measured surface-state energies with those calculated for possible interface bonding arrangements. The atomically abrupt interface...SiAsGaAs, in addition to being energetically very unfavorable, is inconsistent with measured valence-band photoemission spectroscopy. Our results indicate that the interface is not atomically abrupt.