SPECTROSCOPY OF INTERFACE STATES OF INDIUM-SI(111) (4X1) AND (1X1) R30-DEGREES SURFACES

The electronic structure of the In-Si(111)(4 x 1) and (1 x 1)R30-degre es surfaces has been investigated by k-resolved direct and inverse UV photoemission spectroscopy. Spectral features are identified in terms of In-Si interface states, overlayer-induced image potential barrier r esonances, and Si bulk states using the respective energy versus k(par allel-to) plots; the interface states are particularly pronounced in t he inverse photoemission spectra. The interface states associated with the (4 x 1) and the (1 x 1)R30-degrees surfaces are significantly dif ferent with respect to each other and are distinguished from those at the In-Si(square-root 3 x square-root 3)R30-degrees reconstruction. Th is is taken as an indication of different local bonding geometries of In adatoms in the different ordered In-Si surfaces.