中文摘要：

用MOCVD技术生长GaN：Mg外延膜，在550～950℃温度范围内，对样品进行热退火，并进行室温Hall、光致发光谱（PL）测试．Hall测试结果表明，850℃退火后空穴浓度达到8×10^17cm^-3以上，电阻率降到0．8Ω·cm以下．室温PL谱有两个缺陷相关发光峰，位于2．8eV的蓝光峰（BL）以及3．27eV附近的紫外峰（UVL）．蓝光峰对紫外峰的相对强度（BL／UVL）在550℃退火后升高，之后随着退火温度的升高（650-850℃）而下降，继续提高退火温度至950℃，BL／UVL急剧上升．空穴浓度先随着Mg掺杂浓度的增加而升高；但继续增加Mg掺杂浓度，空穴浓度反而下降．这些结果表明要实现空穴浓度达10^18cm^-3，不仅要考虑H的钝化作用，还要考虑Mg受主的自补偿效应．

英文摘要：

Mg-doped GaN layers prepared by metalorganic chemical vapor deposition were annealed at temperatures between 550 and 950℃. Room temperature （RT） Hall and photoluminescence （PL） spectroscopy measurements were performed on the as-grown and annealed samples. After annealing at 850℃, a high hole concentration of 8 × 10^17 cm^-3 and a resistivity of 0. 8lΩ·cm are obtained. Two dominant defect-related PL emission bands in GaN.. Mg are investigated; the blue band is centered at 2. 8eV （BL） and the ultraviolet emission band is around 3.27eV （UVL）. The relative intensity of BL to UVL increases after annealing at 550℃, but decreases when the annealing temperature is raised from 650 to 850℃, and finally increases sharply when the annealing temperature is raised to 950~C. The hole concentration increases with increased Mg doping, and decreases for higher Mg doping concentrations. These results indicate that the difficulties in achieving high hole concentration of 10^18cm^-3 appear to be related not only to hydrogen passivation, but also to self-compensation.