Heterointerface point defects in GaN/AlN quantum wells

On the base of density functional theory (DFT) calculations, it was ascertained that the GaN/AlN heterointerfaces without Al and Ga contacting layers intermixing and with the total substitution of the contacting layers are energetically more probable than the heterointerfaces with another amount of intermixing. The displacement of nitrogen atom from its site to second coordinate sphere between Ga and Al contacting layers is more probable than the displacement to the Al part of the cluster. The presence of nitrogen atom vacancy in the heterointerface does not influence the Al and Ga contacting layers intermixing, but complex defect nitrogen vacancy + interstitial N atom in the second coordinate sphere can be stable in contrast to the case of Al vacancy + interstitial Al atom in the second coordinate sphere. On the base of comparison of calculated and experimental data, it was ascertained that the most probable location of nitrogen vacancy in the vicinity of GaN/AlN interface is the location in the first Ga layer in respect to the GaN/AlN interface.