Effects of 600 °C annealing prior to activation annealing of Mg-ion-implanted GaN on subsequently formed MOS interfaces

Abstract We have investigated the effects of annealing at 600 °C for 3 h prior to rapid thermal annealing (RTA) of Mg-ion-implanted GaN at 1250 °C for 1 min on the properties of subsequently formed metal-oxide-semiconductor (MOS) interfaces. We found that this two-step cap annealing can reduce the gap state density ( D T ) at the subsequently formed GaN MOS interfaces compared with one-step high-temperature RTA. Based on the capacitance–voltage method, the measured D T of a two-step-annealing sample was on the order of 10 10 cm –2 eV –1 at 0.40–0.45 eV below the conduction band edge. In addition, the interface charges originating from near-surface defects were also reduced by adding 600 °C/3 h pre-annealing to conventional RTA. The effects of cap material used in 600 °C annealing were also examined. We found that AlON was superior to Al 2 O 3 and SiN concerning interface states and near-surface defects in the final MOS structures.