For non-polar and semipolar orientations of GaN heteroepitaxially grown on sapphire substrates, the development of growth procedures to improve surface morphology and microstructure was driven in a largely empirical way. This work attempts to comprehensively link the intrinsic properties of GaN faceted growth, across orientations, in order to understand, design and control growth methods for nonpolar (11•0) GaN and semipolar (11•2) GaN on foreign substrates. This was done by constructing a comprehensive series of kinetic Wulff plots (or v-plots) by monitoring the advances of convex and concave facets in selective area growth. A methodology was developed to apply the experimentally determined v-plots to the interpretation and design of evolution dynamics in nucleation and island coalescence. This methodology offers a cohesive and rational model for GaN heteroepitaxy along polar, nonpolar and semipolar orientations, and was broadly extensible to the heteroepitaxy of other materials. It was further demonstrated that the control of morphological evolution, based upon invoking a detailed knowledge of the v-plots, held the key to the reduction of microstructural defects through effective bending of dislocations and blocking of stacking faults.

Using the Kinetic Wulff Plot to Design and Control Nonpolar and Semipolar GaN Heteroepitaxy. B.Leung, Q.Sun, C.D.Yerino, J.Han, M.E.Coltrin: Semiconductor Science and Technology, 2012, 27[2], 024005