First principles investigation of the structural and electronic properties of (110), (110) and (111) growth axis AlN/GaN superlattices

First-principles calculations are performed to study the structural and electronic properties of AlN and GaN zinc-blende/zinc-blende superlattices using the full potential linear muffin-tin orbitals (FPLMTO) method in its plane wave approximation (PLW) which enables an accurate treatment of the interstitial regions. Choosing this method ensures that the present work is free from adjustable parameters and enabled us to perform a microscopic study. The results for AlN/GaN superlattices (SLs) with the three directions (001), (110) and (111) are investigated and compared. The electronic structures of the (001), (110) and (111) growth axis SLs are calculated, and it is shown that the analysis of the partial density of states reveals that the reductions and modifications of the nature of the gaps in (110) and (111) growth axis SLs can be explained by the strong pd and sp hybridization of the Ga and N atoms.