Optical excitation at 1.7K with 364nm laser light produces partial annealing recovery of the damage produced in GaN by 2.5MeV electron irradiation in situ at 4.2K. Observed was a reduction in the irradiation-produced 0.95eV photoluminescence band, recovery in the visible luminescence, and conversion between the 2 electron-paramagnetic-resonance signals L5 and L6 associated with interstitial Ga. This was interpreted as resulting from electronically excited migration of the interstitial Ga allowing it to convert between lattice sites near the Ga vacancy from which it was ejected. The relative rates of conversion between the two sites were found to vary between different samples and upon electron irradiation fluence.

Intrinsic Defects in GaN - II. Electronically Enhanced Migration of Interstitial Ga Observed by Optical Detection of Electron Paramagnetic Resonance. P.Johannesen, A.Zakrzewski, L.S.Vlasenko, G.D.Watkins, A.Usui, H.Sunakawa, M.Mizuta: Physical Review B, 2004, 69[4], 045208 (5pp)