论文部分内容阅读
用MOCVD方法在 (0 0 0 1)取向的蓝宝石 (α -Al2 O3)衬底上生长了不同势垒层厚度的Al0 .2 2Ga0 .78N/GaN异质结构 ,利用高分辨X射线衍射 (HRXRD)测量了其对称反射 (0 0 0 2 )和非对称反射 (10 14 )的倒易空间图 (RSM )。分析结果表明 ,势垒层内部微结构与应变状态和下层i -GaN的微结构与应变状态互相关联 ,当厚度大于 75 0 时 ,势垒层开始发生应变弛豫 ,临界厚度大于5 0 0 。势垒层具有一种“非常规”应变弛豫状态 ,这种状态的来源可能与n -AlGaN的内部缺陷以及i-GaN/α -Al2 O3界面应变弛豫状态有关
Al0.22Ga0.78N / GaN heterostructures with different barrier layer thicknesses were grown on (0 0 0 1) oriented sapphire substrate by MOCVD. High resolution X-ray diffraction (HRXRD ) Measured the reciprocal space map (RSM) of its symmetric reflection (0 0 0 2) and asymmetric reflection (10 14). The analysis results show that the microstructure and strain state of the barrier layer are related to the microstructure and strain state of the underlying i-GaN. When the thickness is larger than 75 0, the barrier layer begins to strain relax and the critical thickness is more than 500. The barrier layer has an “unconventional” strain relaxation state, the origin of which may be related to the internal defects of n-AlGaN and the strain relaxation state of the i-GaN / α-Al 2 O 3 interface