Microscopic mapping of strain relaxation in uncoalesced pendeoepitaxial GaN on SiC

Mapping of the strain distribution in uncoalesced pendeoepitaxial GaN on SiC by spatially resolved micro-Raman and microphotoluminescence, and lattice constants measured by high-resolution x-ray diffraction provide a consistent picture of relaxation of inhomogeneous and anisotropic strain. The pendeoepitaxial wings show a nearly complete strain relaxation and high optical quality with extremely narrow donor bound exciton peaks. The narrow exciton linewidths result in the determination of c-axis strain to an accuracy of $6\times {10}^{-6}.$