Defect states of complexes involving a vacancy on the boron site in boronitrene

Abstract

First principles calculations have been performed to investigate the ground state properties of freestanding monolayer hexagonal boronitrene (h-BN). We have considered monolayers that contain native point defects and their complexes, which form when the point defects bind with the boron vacancy on the nearest neighbour position. The changes in the electronic structure are analysed to show the extent of localization of the defect-induced mid-gap states. The variations in formation energies suggest that defective h-BN monolayers that contain carbon substitutional impurities are the most stable structures irrespective of the changes in growth conditions. The high energies of formation of the boron vacancy complexes suggest that they are less stable, and their creation by ion bombardment would require high energy ions compared to point defects. Using the relative positions of the derived mid-gap levels for the double vacancy complex, it is shown that the quasi donor-acceptor pair interpretation of optical transitions is consistent with stimulated transitions between electron–hole states in boronitrene.