Comparison of atomistic and continuum theoretical approaches to determine electronic properties of GaN/AlN quantum dots

In this work we present a comparison of multiband k·models, the effective-bond-orbital approach, and an empirical tight-binding model to calculate the electronic structure for the example of a truncated pyramidal GaN/AlN self-assembled quantum dot with a zinc-blende structure. For the system under consideration, we find very good agreement between the results of the microscopic models and the eight-band k·p formalism, in contrast to a 6+2 -band k·p model, where conduction band and valence band are assumed to be decoupled. This indicates a surprisingly strong coupling between conduction- and valence-band states for the wide-band-gap materials GaN and AlN. Special attention is paid to the possible influence of the weak spin-orbit coupling on the localized single-particle wave functions of the investigated structure.