Tight-binding theory of heterojunction band lineups and interface dipoles

Abstract

A tight-binding theory of semiconductor heterojunction band lineups is presented. Interface dipoles are shown to play a crucial role in determining lineups, so that lineups obtained by using the vacuum level as a reference (e.g., the electron affinity rule) are not reliable. Instead, the self-consistent lineup can be obtained approximately by aligning the average sp3 hybrid energies in the respective semiconductors. Numerical results are provided and compared with experiment, and the approximations and accuracy in this approach are discussed. The application of these ideas to Schottky barriers is also considered.