LAUSR

Abstract We have carried out the density functional theory calculations of vacancies in monolayer h-BN. We model five configurations, two configurations of monovacancies ( V B and V N ) and three configurations ( V B B , V N N , and V B N ) of divacancies. In the case of monovacancies, we find that V B and V N form a C3V symmetry. In the divacancy case, we find that V N N produces a heart-like configuration having two pentagons and leaving two dangling bonds, while V B B leaves four dangling bonds. As for V B N , it produces two pentagons and has no dangling bond. The calculated formation energies of V B , V N , V B B , V N N , and V B N are 11.65 eV, 12.05 eV, 17.59 eV, 22.32 eV, and 16.89 eV, respectively. These energies show that V B is more stable than V N , while V B B is more stable than V N N . We conclude that the N-rich h-BN sheet is energetically more favorable to be formed rather than the B-rich one. However, the most stable configuration of the divacancies belongs to V B N compensating from the absence of the dangling bond, which obeys the dangling-bond-counting-model. Furthermore, we calculate band structures of the most stable mono- and divacancies. We find that monovacancy somewhat changes the electronic structure, shown by localized states near the Fermi level, while the divacancy produces two new states above the Fermi level.