Tight Binding Modeling of Heterojunction Band Offsets as a Function of Pressure and Composition

Abstract

We present a new tight binding view of the heterojunction band offsets. The model considers the nonorthogonality of the sp3 set of orbitals of adjacent atoms and spin–orbit coupling and uses the Hartre-Fock atomic energies and interacting matrix element, obtained by fitting bulk band structures of semiconductors, to determine the valence band energies at 0 K and 1 bar. The valence band offsets are then obtained by aligning the temperature, pressure, and composition dependent vacuum levels, screened by the optical dielectric constants of bulk materials for thermodynamic equilibrium across heterointerfaces. Excellent agreement between the model predictions and experiment for the valence band offsets suggests that the bulk band structure properties play a significant role in determining the band offsets for lattice matched heterojunctions and Schottky barriers.