Intrinsic defects in GaN. II. Electronically enhanced migration of interstitial Ga observed by optical detection of electron paramagnetic resonance

Abstract

Optical excitation at 1.7 K with 364-nm laser light produces partial annealing recovery of the damage produced in GaN by 2.5-MeV electron irradiation in situ at 4.2 K. Observed is a reduction in the irradiation-produced 0.95-eV photoluminescence (PL) band, recovery in the visible luminescence, and conversion between the two electron-paramagnetic-resonance (ODEPR) signals L5 and L6 associated with interstitial Ga. This is 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 are found to vary between different samples and upon electron irradiation fluence.