Triangle defect states of hexagonal boron nitride atomic layer: Density functional theory calculations

Triangle defect states of hexagonal boron nitride ($h$-BN) atomic layer were studied by a density functional theory calculation. N(B) triangle defect states of $h$-BN atomic layer with N(B) edge atoms have acceptor (donor) levels. A cohesive energy calculation indicates that the $h$-BN atomic layer with N triangle defects is more or less stable, respectively, than that with B triangle defects when it is negatively or positively charged, which is consistent with the recent experimental observation of N triangle defects in $h$-BN atomic layer. Charge population analysis shows that the edge N(B) atoms surrounding the N(B) triangle defect are negatively (positively) charged. Such a charged triangle defects in $h$-BN may serve as a potential nanolens for electron-beam focusing.