Optimization of initial MOVPE growth of non-polar m- and a-plane GaN on Na flux grown LPE-GaN substrates

We optimized the initial GaN growths of nonpolar mand a-plane GaN grown on liquid phase epitaxy (LPE-) GaN substrates. Such nonpolar LPE-GaN substrates were produced by cutting slices from c-plane LPE-GaN bulk single crystals grown by the Na-flux method. We investigated the qualities of epitaxially grown GaN layers on the LPE-GaN substrates, with different polishing methods, which are chemical mechanical polishing and plasma dry etch polishing. We found that the crystalline quality of epitaxial GaN on m-plane GaN is very sensitive to the surface polishing even the minute unevenness in GaN substrate. Our experiments also indicated that a low initial growth rate was necessary to obtain high-crystallinequality epitaxial m-plane GaN. In contrast, highcrystalline-quality a-plane GaN was obtained even with a high initial growth rate, indicating that the crystalline quality of a-plane GaN is not sensitive to surface roughness. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim