Stress analysis of selective epitaxial growth of GaN

Stress distributions in selectively overgrown self-organized GaN hexagonal pyramids have been analyzed by continuum elasticity theory. This has been carried out using the values for the moduli of elasticity found in the literature and an effective lattice mismatch between the GaN and the substrate that was determined from the Raman shift of the GaN buffer layer. The results of compressive stress in the buffer layer, tensile stress on the lower half of the pyramids’ facet surface, and full relaxation for approximately the upper 2/3 of the pyramids are in satisfactory agreement with the experimental observations that were deduced from cathodoluminescence microscopy and micro-Raman spectroscopy.