  The formation energies and transition energy levels of native defects in
hexagonal BN have been studied by first-principles calculations based on hybrid
density functional theory (DFT) together with an empirical dispersion
correction of Grimme's DFT-D2 method. Our calculated results predict that the
interstitial B is the most stable defect under N-rich and p-type conditions.
While the B vacancy and interstitial N become the dominate defects when the
electron chemical potential is near the conduction band maximum of host.
Nevertheless, these compensating defects would be inactive due to their ultra
deep ionization levels under both p- and n-type conditions.
