Ab initio calculations of charged point defects in GaN

The Generalized Gradient Approximation (GGA) of a Density Functional Theory (DFT) in LCAO basis is used to determine electronic structure of charged point defects in hexagonal GaN. Impurities of Mg_Ga, Zn_Ga, Si_N and C_N (the most common dopants) were considered for charge states 0, ±1, -2. The vacancies of VG_a and V _N were considered for charge states 0 and 0, ±1, ±2 respectively. The defects in consideration are compared from the point of view of the one-electron states localization. All the calculations were performed for a supercell containing 96 atoms. The divergence due to periodically repeated charges has been eliminated by the use of a uniform background charge of an opposite sign.