Low-temperature formation of metal/molecular-beam epitaxy

We report soft x-ray photoemission studies of metal/molecular-beam epitaxy (MBE)GaAs(lOO) interfaces formed at low temperature. Our results indicate that rectifying barrier heights are proportional to the metal work function in accordance with Schottky's original description of metal-semiconductor contacts. These results confirm the predictions of a selfconsistent model of metal-semiconductor interfaces, and suggest that metal-induced gap states and native defect mechanisms are not major factors in determining the Fermi level energy at "ideal" interfaces. We attribute deviations from the ideal Schottky limit behavior observed for interfaces formed at room temperature to metallization-induced atomic relaxations (rather than electronic relaxations) occurring at metal-semiconductor contacts. We present a useful methodology for analyzing electronic properties at metal-semiconductor interfaces. The pronounced differences in barrier height formation between MBE vs melt-grown GaAs can evidence the role of deep states in controlling Schottky barriers at metal/melt-grown GaAs.