Activation of p-type GaN in a pure oxygen ambient

In this study, we activated p-type GaN in a pure oxygen ambient by rapid thermal annealing. The sheet resistance of p-type GaN was greatly reduced from > 10⁷ Ω/□ to 7.06 × 10⁴ Ω/□ after annealing in oxygen ambient at 500°C. The photoluminescence intensity of blue emission increased by one order of magnitude compared to the as-grown sample. Moreover, the sheet resistance of p-type GaN annealed in pure oxygen ambient is lower than that of p-type GaN annealed in nitrogen ambient. The carrier concentrations of the samples annealed in oxygen ambient are higher than those annealed in nitrogen ambient. The better activation of p-type GaN in oxygen ambient is due to the higher activity of oxygen than that of nitrogen. Oxygen would remove hydrogen that passivates Mg atoms by forming H₂O at a lower temperature.