An ab initio-based approach for the formation of pyramidal inversion domain boundaries in highly Mg-doped GaN

Abstract The formation of pyramidal inversion domain (PID) boundaries in highly Mg-doped GaN is investigated on the basis of ab initio calculations. Results for the absolute interface energies of PID boundaries reveal that their upper (0001) and side {11 2 ¯ 3} facets hosting Mg atoms are stable owing to the electron counting rule. Furthermore, with these absolute interface energies, the formation energies for various PID boundaries of varying sizes and concentrations were estimated. Energy comparisons with those of substitutional Mg demonstrate that the formation of large PID boundaries is preferred when numerous Mg atoms are incorporated in the GaN matrix. The results suggest that the formation of PID boundaries is crucial for Mg doping and the resulting hole concentrations.