A positive test of the LCAO theory of heterojunctions: Microscopic measurements of band discontinuities at CdS–Ge and InP–Ge interfaces

Abstract

The formation of CdS–Ge and InP–Ge interfaces was studied during its early stages of soft‐x‐ray photoemission spectroscopy. The experimental spectra of the valence‐band region and of several p and d core levels give an estimate of the valence‐band discontinuity at the interface. The measured discontinuity values, 0.5±0.1 eV for InP–Ge and 1.8(3)±0.1 eV for CdS–Ge are close to the theoretical prediction of Harrison’s LCAO approach. These and similar results for other interfaces greatly enhance the hope for the development of an elementary theory of the heterojunction parameters.