Effect of controlled growth dynamics on the microstructure of nonpolar a-plane GaN revealed by X-ray diffraction

This paper reports the effect of controlled growth dynamics, as monitored by in situ optical reflectance, on the microstructure of nonpolar aplane GaN films grown on r-plane sapphire. The mosaic microstructure of a-plane GaN and its anisotropy are evaluated by X-ray rocking curve (XRC) measurements. By inserting a pronounced islanding stage followed by an enhanced lateral growth, pit-free a-plane GaN has been achieved showing an XRC linewidth of -0:18 and -0:3° for on- and off-axes planes, respectively, with only minor anisotropy. The density of basal-plane stacking faults is reduced by -70% as determined by a modified Williamson-Hall X-ray analysis.