Study on MOCVD-grown Mg-doped GaN by annealing treatment

Mg-doped GaN epilayers are grown on 50 mm basal plane sapphire substrates by metalorganic chemical vapor deposition. Thermal annealing treatments are carried out on the samples and Hall, double crystal X-ray diffraction, and photoluminescence (PL) spectroscopy measurements are performed on the as-grown and annealed samples, respectively. The Hall measurements show that after annealing at 950°C, the sample has a hole concentration of 5 × 1017 cm-3 and a resistivity of 2.5 Ω&middotcm. The X-ray (0002) diffraction measurement shows that the as-grown and annealed samples have the same full width at half maximum of 4arcmin. A dominant PL peak around 2.85 eV is observed at room temperature PL spectra both on the as-grown and the annealed samples, and the intensity of this PL peak of the annealed samples is eight times stronger than that of the as-grown ones. It can be concluded that large numbers of Mg atoms passivated by H atoms in the as-grown GaN epilayers are electrically activated by the annealing treatment.