Optically detected magnetic-resonance experiments on as-grown Mg-doped GaN produced by metal-organic vapor phase epitaxy revealed the presence of a triplet state spectrum with a zero-field splitting that corresponded to a pair of centers, each with a

spin of 1/2, strongly coupled by an exchange interaction and separated in the direction of the c axis by 0.26nm. The spectra showed no resolved hyperfine structure, suggesting that the centers involve elements with zero nuclear spin. The separation of 0.26nm corresponded to the distance between two octahedral interstitial sites, suggesting that the spectrum was due to an interstitial-interstitial pair, possibly involving Mg and O.

Optically Detected Magnetic Resonance of Paired Defects in As-Grown Magnesium-Doped GaN. J.J.Davies, G.N.Aliev, S.J.Bingham, D.Wolverson, S.Stepanov, B.Yavich, W.N.Wang: Physical Review B, 2003, 67[3], 035203 (7pp)