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 a-plane 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 similar to 0.18 and similar to 0.3 degrees for on- and off-axes planes, respectively, with only minor anisotropy. The density of basal-plane stacking faults is reduced by similar to 70% as determined by a modified Williamson-Hall X-ray analysis. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.071002