Luminescence Properties of Epitaxially Grown GaN and InGaN Layers Around ZnO Nanopillars

GaN and InGaN layers grown around ZnO nanopillars by metalorganic vapor phase epitaxy (MOVPE) are investigated by means of photoluminescence (PL) and locally resolved cathodoluminescence (CL). A multi layer growth process involving deposition at different growth conditions in a step-wise manner has been employed for the coaxially grown GaN. Then InGaN/GaN quantum wells and barriers have been deposited as the final growth stage. A sharp peak at 3.46 eV in low temperature PL with FWHM of 23meV confirmed the high quality of the deposited GaN layers. The existence of InGaN layers has been confirmed by another PL peak at 3.16 eV that has been shifted to 3.11 eV as the InGaN deposition temperature was reduced by 15 C and the trimethylindium (TMIn) flow was increased by 40 sccm. For more efficient investigations of single pillars, position control has been achieved through the growth of single ZnO nanopillars on top of GaN pyramids. Locally resolved CL mapping along single rods has revealed a relatively homogeneous indium distribution along the nonpolar side facets of the overgrown nano-pillars.