Band Offsets in Lattice-Matched Heterojunctions: A Model and First-Principles Calculations for GaAs/AlAs

A new model for band offsets in lattice-matched heterojunctions is presented along with a novel definition of the interface dipole which avoids any reference to an ideal interface. The model is derived only from the charge densities of the bulk constituents and naturally predicts the independence of the offsets on interface geometry. It is in excellent agreement with accurate first-principles pseudopotential calculations for ${(\mathrm{GaAs})}_{3}$/${(\mathrm{AlAs})}_{3}$ grown in the (001), (110), and (111) directions and with available experimental data.