Improvement in the crystal quality of non-polar a-plane GaN directly grown on an SiO2 stripe-patterned r-plane sapphire substrate
We studied the non-polar a-plane GaN directly grown on an SiO2 stripe-patterned r-plane sapphire substrate along the  crystallographic direction of GaN. The XRC-FWHM values of the optimized a-plane GaN were 386 arcsec along the c-axis and 289 arcsec along the m-axis. Detailed scanning electron microscopy (SEM), X-ray diffraction (XRD) reciprocal space maps (RSMs) and Raman scattering studies were performed to investigate the growth kinetics. It was found that the increase in mosaic block dimension could be the primary reason for the improved crystal quality. This work shows a very promising and simple method to achieve high-quality a-plane GaN films.