(7x7) reconstruction as barrier for Schottky-barrier formation at the Ga/Si(111) interface

We report the change in electronic properties of the Ga/Si interface by monitoring the Ga(3d) core-level photoelectron spectra and electron diffraction induced by submonolayer Ga adsorption on Si(111)-7x7 surface. The spectra shows a flat band for submonolayer coverages, attributed to the metallic nature of the Si(111)-7x7 reconstruction and a premetallic band structure of two-dimensional Ga islands. At 1 ML, electron diffraction pattern shows metallic (7x7) to semiconducting (1x1) phase-transition and the spin-orbit split branching ratio of Ga(2p) core level attain the metallic bulk value, and the barrier assumes the Schottky-Mott value while full width half maxima and branching ratio attain bulk values. (C) 2010 American Institute of Physics. [doi:10.1063/1.3490250]