Theory of oxygen-boron vacancy defect in cubic boron nitride: A diamond NV-isoelectronic center

A color center in c-BN which is isoelectronic to diamond NV- is predicted based on first-principles electronic structure calculations using the Heyd-Scuseria-Ernzerhof hybrid functional. The defect consists of a substitutional oxygen and an adjacent boron vacancy (ON-VB). We find that the ON-VB center is optically accessible with a zero-phonon line of about 1.6 eV. The ON-VB center also shares much of the characteristics of the GC-2 center often observed in c-BN. A prominent vibronic coupling peak is predicted to be around 55 meV, which is in excellent agreement with the characteristic phonon frequency (56 meV) observed in the luminescence spectra of the GC-2 center.