We report on the impact of growth conditions on surface hillock density of N-polar GaN grown on nominally on-axis (0001) sapphire substrate by metal organic chemical vapor deposition (MOCVD). Large reduction in hillock density was achieved by implementation of an optimized high temperature AlN nucleation layer and use of indium surfactant in GaN overgrowth. A reduction by more than a factor of five in hillock density from 1000 to 170 hillocks/cm −2 was achieved as a result. Crystal quality and surface morphology of the resultant GaN films were characterized by high resolution x-ray diffraction and atomic force microscopy and found to be relatively unaffected by the buffer conditions. It is also shown that the density of smaller surface features is unaffected by AlN buffer conditions.

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Growth of GaN on rare earth oxide (REO) buffers grown on silicon (111) was performed. A novel low temperature buffer layer was developed in order to suppress the decomposition of the REO buffer under hydrogen flow during MOCVD. GaN films, grown by this technique, exhibit smooth surface morphologies. XRD studies reveal the formation of an ErN layer during growth. 10.1149/05804.0455ecst ©The Electrochemical Society ECS Transactions, 58 (4) 455-461 (2013) 455 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-06-10 to IP