Cubic inclusions in hexagonal AlN , GaN , and InN : Electronic states

Modern quasiparticle calculations based on hybrid functionals and the GW approximation or a transition-state approach are used to predict natural band discontinuities between wurtzite and zinc-blende polytypes of AlN, GaN, and InN by two alignment methods, a modified Tersoff method for the branch-point energy and the Shockley-Anderson model aligning electrostatic potentials. We find a type-I heterostructure behavior for cubic layers embedded in wurtzite for GaN and InN, while AlN tends to a type-II heterostructure behavior. In addition, the electronic states of wurtzite-zinc-blende superlattices are studied in detail with respect to their energy position and wave-function localization. While the lowest electron states are localized in the cubic inclusion for all nitrides, the localization of the uppermost hole states is less clear but tends to be in the hexagonal matrix. The influence of the built-in internal electric fields is discussed.