Journal of Crystal Growth, Vol.348, No.1, 10-14, 2012
Growth of a-plane GaN on r-plane sapphire by self-patterned nanoscale epitaxial lateral overgrowth
We report on the use of a novel technique to grow the nonpolar a-plane GaN on r-plane sapphire by metal-organic chemical vapor deposition. A thin InGaN interlayer was deposited on the substrate followed by a low temperature (LT) GaN buffer layer. A stripe-like template was obtained by annealing the LT GaN/InGaN layers at 1100 degrees C for 2 min. This special template facilitated the nanoscale epitaxial lateral overgrowth of a-plane GaN. Scanning electron microscopy shows that the surface morphology was rather flat for a 1 mu m-thick sample. The improvement in crystalline quality was also demonstrated by high-resolution x-ray diffraction, room temperature Raman spectroscopy and photoluminescence measurements. Compared with the traditional epitaxial lateral overgrowth technique, our technique greatly simplified the template preparing process and the crystalline quality of a-plane GaN was improved. (C) 2012 Elsevier B.V. All rights reserved.