SiC衬底上生长的GaN外延层的高分辨X射线衍射分析

High Resolution X-ray Diffraction Analysis of GaN Epitaxial Layer Grown on SiC Substrate

通过高分辨X射线衍射(HRXRD)技术,对金属有机化合物气相外延(MOCVD)生长的GaN外延膜及SiC衬底的相对取向,晶格常数和应力情况,位错密度等进行了分析。分析表明,GaN和SiC具有一致的a轴取向,GaN外延层弛豫度超过90%,GaN外延层的晶格常数与体块材料相近,在GaN中存在压应力,SiC衬底和GaN外延层中的位错密度分别为107和108量级。

The GaN epitaxial layer grown on SiC substrate by metal-organic chemical vapor dispersion was analyzed by the high resolution X-ray diffraction （HRXRD）. The orientation of the GaN relative to the SiC, the lattice parameters, the stress and the dislocation density were detected. The analysis results indicate that the a-axis direction of GaN is parallel to that of SiC. The relaxation degrade of the GaN epitaxial layer exceeds 90% and the lattice parameters of GaN epitaxial layes are almost the same as those of bulk GaN material. The GaN layer is compressive stressed. The dislocation densities in SiC and GaN are 10^7 and 10^8 respectively.