Defects in AIN/GaN Superlattice: First Principle Calculations.

Abstract

In this paper we investigate the atomic configurations, electronic structure and formation energies of native point defects, (such as vacancies and self-interstitials), in an AIN/GaN superlattice (SL) constructed on a wurtzite structure along a [0001] growth direction. Comprehensive first-principle calculations based on the density functional theory (DFT) are used. Cation and anion vacancies in the neutral charge state are calculated. For the native defects, the results showed that the most favorable configurations are the cation vacancies at the interface of the SL, or the anion vacancies in the GaN wells. Considering the formation energies of different vacancies, the results show that the nitrogen vacancy has the lowest formation energy, indicating that they are significantly the most stable configuration, and thus should be expected to be the major defect in a AIN/GaN superlattice.