Electronic structure of the Na-adsorbed Si(100)2 x 1 surface studied by inverse and direct angle-resolved photoemission.

Abstract

The surface electronic band structure of the Na-saturated Si(100)2×1 surface has been studied with angle-resolved inverse and direct photoemission. Single-domain 2×1-reconstructed surfaces were obtained by using vicinal samples. At a sodium coverage of roughly half the saturation coverage, an overlayer-derived empty surface state appears at the Γ point 1.5 eV above the Fermi level. With increasing Na coverage, it moves downward in energy to 0.7 eV at saturation, where it displays a weak upward dispersion along both the Γ-J and the Γ-J' direction