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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8×1017cm-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1018cm-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.
The GaN epitaxial films were grown by MOCVD, and the samples were annealed at room temperature from 550 ℃ to 950 ℃, and Hall and PL measurements were carried out at room temperature.The results of Hall test showed that after annealing at 850 ℃, At a concentration above 8 × 10 17 cm -3, the resistivity dropped below 0.8 Ω · cm. The PL spectrum at room temperature had two defect-related luminescence peaks at a blue peak of 2.8 eV (BL) and a UV peak of 3.27 eV. The relative intensities (BL / UVL) of the blue peak to the UV peak increased after annealing at 550 ° C and then decreased as the annealing temperature increased (650-850 ° C). The annealing temperature was further increased to 950 ° C. BL / UVL was abrupt The hole concentration first increases with the increase of Mg doping concentration, but the concentration of Mg doping increases but the hole concentration decreases, and these results show that to achieve the hole concentration of 1018cm-3, not only H Passivation, but also consider the self-compensation effect of Mg acceptor.