Crystallographic Orientation and Strain in GaN Crystals Grown on 6H-SiC and Sapphire Substrates

The crystallographic-orientation relationship between GaN crystals grown via hydride vapor phase epitaxy (HVPE) on 6H-SiC was investigated. This study employed electron backscatter diffraction (EBSD) Kikuchi diffraction patterns and pole figures to identify this relationship and calculate lattice mismatches. Comparing the misorientation of GaN crystals on different substrates along the growth direction using EBSD mapping, we identify the strain in GaN based on crystallographic-orientation results. Raman spectroscopy results correlate residual stress in GaN with lattice mismatches, aligning with our previous works. Residual stress of GaN on different substrates identified using PL spectrum also confirmed these results. The HRXRD characterized the dislocation density of GaN crystals grown on these substrates.