The thermal quenching of an infra-red deep level of 1.2 to 1.5eV was investigated in Mg-doped p-type films by using 1-step and 2-step annealing and photo-current measurements. The deep level appeared during 1-step annealing at the relatively high temperature of 900C, but disappeared during 2-step annealing involving a low-temperature step and a subsequent high-temperature step. The persistent photo-current was residual in samples with the deep level, but terminated in samples without the deep level. This indicated that the deep level was a neutral hole center located above a quasi-Fermi level; with an energy at 0.1 to 0.15eV above the valence band, at a hole carrier concentration of 2.0 x 1017 to 2.5 x 1017/cm3.

Thermal Quenching Effect of an Infrared Deep Level in Mg-Doped p-Type GaN Films. K.Kim, S.J.Chung: Applied Physics Letters, 2002, 80[10], 1767-9