First principles studies on In-related nitride semiconductors

In-related nitride semiconductors exhibit characteristic behavior which can be ascribed to the large difference in the covalent radius between In and N atoms. We consider atomic and electronic structures of N mono-vacancies (VN) in InGaN in detail by the first principles calculations. We find that the second nearest neighbor In–In interactions, which are not important in conventional semiconductors such as Si and InAs, are as crucial as the nearest neighbor In–N interaction in In-related nitride semiconductors. Moreover, we clearly show that the strong second nearest neighbor In–In interactions in InN are the physical origin of the unusually narrow band gap of InN.