Mg+注入对GaN晶体辐射损伤的研究

在蓝宝石衬底上通过金属有机物化学气相沉积(metal-organic chemical vapor deposition，MOCVD)方法外延生长的GaN薄膜具有良好的结晶品质，χ_min达到2.00%. 结合卢瑟福背散射/沟道(Rutherford backscattering/channeling，RBS/C)和高分辨X射线衍射(high-resolution X-ray diffraction，HXRD)的实验测量，研究了不同剂量和不同角度Mg⁺注入GaN所造成的辐射损伤. 实验结果表明，随注入剂量的增大，晶体的辐射损伤也增大，注入剂量在1×10¹⁵atom/cm²以下，χ_min小于4.78%，1×10¹⁶atom/cm²是Mg⁺注入GaN的剂量阈值，超过这个阈值，结晶品质急剧变差，χ_min达到29.5%；随机注入比沟道注入的辐射损伤大，且在一定范围内随注入角度的增大，损伤也增大，在4×10¹⁵atom/cm²剂量下偏离〈0001〉沟道0°，4°，6°，9°时的χ_min(%)分别为6.28，8.46，10.06，10.85；经过700℃/10min+1050℃/20s两步退火和1000℃/30s高温快速退火后，晶体的辐射损伤都有一定程度的恢复，而且1000℃/30s高温快速退火的效果更好，晶体的辐射损伤可以得到更好的恢复. 关键词： GaN 卢瑟福被散射/沟道 高分辨X射线衍射 辐射损伤

Study of radiation damage in Mg+-implanted GaN

The GaN films grown on sapphire by metal-organic chemical vapor deposition (MOCVD) have excellent crystalline quality (χ_min=2.00%). Combining Rutherford backscattering/channeling (RBS/C) and high-resolution X-ray diffraction (HXRD) measurements, we investigate the radiation damage in GaN films with various doses and angles of Mg⁺-implantation. The results of experiments reveal that the radiation damage rises with the increasing implantation dose. Under the dose of 1×10¹⁵atom/cm², χ_min is less than 4.78%, and when implantation dose exceeds the threshold of 1×10¹⁶atom/cm², χ_min will be up to 29.5%. Random implantation causes more serious damage than channeled implantation, and in a definite range the damage level rises with a larger implantation angle. At the implantation angles of 0°,4°,6°and 9°deviating from〈0001〉, χ_min(%)is 6.28,8.46,10.06 and 10.85, respectively, at a dose of 4×10¹⁵atom/cm². After annealing at 700℃ for 10min and then 1050℃ for 20s, the damage recovers to some extend. The crystalline quality of the sample with 1×10¹⁶atom/cm² implanted was reduced to 19.08%. In addition, the annealing condition of 1000℃ for 30s is more efficient and the damage recovers better.