Cubic AlGaN/GaN and GaN/InGaN heterostructures:: effects of p-type doping

The effects of p-type doping in cubic AlGaN/GaN and GaN/InGaN heterostructures, such as multiple quantum wells and superlattices are studied through band structure calculations within the effective-mass and the local density functional approximations. The multi-band effective mass equations, within the Luttinger-Kohn model, are solved self-consistently with the Poisson equation by adopting a plane-wave representation. We present results for the hole band structures and different hole potentials as functions of the acceptor doping concentration and superlattice period. Strain effects due to lattice mismatch, and their influence on the hole bands are analyzed. It is shown that a two-dimensional hole gas (2DHG) may occur if appropriate design parameters for well- and barrier-widths are used. The inclusion of the heavy, light, and split-off hole bands, as well as exchange-correlation effects within the 2DHG in the self-consistent calculation of the valence band structure is found to play a fundamental role in a realistic description of the p-doped nitride heterostructures.