Cation vacancies like $V_{\text{Ga}}$, $V_{\text{Al}}$ and their complexes with oxygen are predicted to be abundant in III-nitrides and to play an important role in nonradiative recombination. Appearing in triple or double negatively charged states, they are not paramagnetic and have not so far been detected by magnetic resonance even under illumination. In this Brief Report, we demonstrate an efficient way to make cation vacancy defects in GaN detectable by electron paramagnetic resonance and present our identification of the $V_{\text{Ga}}{\text{O}}_{\text{N}}$ pair in GaN which is the model material for the III-nitrides and their alloys.

• Received 4 July 2009

DOI:https://doi.org/10.1103/PhysRevB.80.153202