Absolute Conduction- and Valence-Band Positions for Ge from an Anisotropic Model of Photoemission

Abstract

An anisotropic direct-transition model for single-crystal semiconductors is shown to predict the direct-transition features seen in experimental photoemission spectra for Ge(111) for $h\nu \lesssim 20$ eV. By comparing theory with experiment, all the conduction and valence bands at $L$ and $X$ within 1 Ry of the gap are determined. Comparison of experiment with current band models suggests that an ∼ 10% self-energy correction may be needed to describe high-energy optical transitions.