Bistable carbon-vacancy defects in h-BN
Song Li, Ádám Gali
Abstract
Single-photon emitters in hexagonal boron nitride have been extensively studied recently. Although unambiguous identification of the emitters is still under intense research, carbon-related defects are believed to play a vital role for the emitter producing zero-phonon lines in the range of 1.6–2.2 eV. In this study, we systematically investigate two configurations of carbon-vacancy defects, V N C B and C N V B , by means of density functional theory calculations. We calculated the reaction barrier energies from one defect to the other to determine relative stability. We find that the barrier energies are charge dependent, and C N V B could easily transform to V N C B in neutral- and positive-charge states while it is stable when negatively charged. Formation energy calculations show that the V N C B is the dominant defect over C N V B . However, neither V N C B nor C N V B has suitable fluorescence spectra that could reproduce the observed ones. Our results indicate that the origin of the 1.6-to-2.2-eV emitters should be other carbon-related configurations.