1. Based on the theory of strain relaxation and investigation by HRXRD, it is indicated the samples with Mn concentration of 2% and 3% are in quasi-coherence or with low relaxation degree, respectively.
2. Crystal constants of samples were obtained by HRXRD characterization, then Mn concentration (0≤x≤0.0681) of each sample can be calculated using Vegard's formula.
3. The HRXRD data presented that the high energy electron irradiation could result into the partial strain relaxation of GaN epitaxial layers.
4. High resolution X-ray diffraction (HRXRD) showed that the crystalline quality of GaN layers was improved by using LT-AlN interlayer.