DFT study on point defects migration through the pseudomorphic and lattice-matched InN/GaN interfaces

Abstract

Diffusion of native point defects is examined in the interface region of the InN/GaN heterostructure grown in hexagonal c direction. Heights of migration energy barriers of single vacancies and their complexes with substitutional group-III element are calculated in bulk GaN and InN crystals for two diffusion mechanisms, as well as across the InN/GaN heterointerface. An impact of the in-plane strain, the influence of built-in electric field, as well as the presence of electric dipole on vacancy motion is analysed. The obtained results show that metal vacancies VGa and VIn can migrate across the InN/GaN interface overcoming a potential energy barrier lower than that of VN. Moreover, the smallest energy barrier is related to the in-plane migration of VIn what can favor spatial segregation of In atoms near the InN/GaN interface. This phenomenon can significantly contribute to the thermal degradation process of InGaN/GaN QWs, often observed experimentally both during the operation of nitride devices, as well as at the stage of their growth.