Electronic structure of thin films of zinc-blende GaN(0 0 1): LCAO calculation

Abstract

Electronic energy spectra of thin films of GaN and the corresponding density-of-states distributions are presented. The (001)-oriented slabs of zinc-blende GaN are considered, with surfaces reconstructed according to the experimental data. Calculations are performed within a semi-empirical LCAO approach. The model parameters are fitted to the bulk electronic structure known from ab initio computations. Empirical corrections are introduced to reproduce the experimental main band gap width as well as the electron affinity. The effect of crystal termination and surface reconstruction is taken into account by an appropriate (self-consistent) change of parameters in the surface region. Dependence of the electronic structure of a thin film on its thickness is analysed. The obtained changes of the highest occupied level as well as the changes of ionic charge in particular GaN ionic layers indicate limited size of stable (001)-oriented GaN thin films.