Growth and characterization of N-polar InGaN∕GaN multiquantum wells

The properties of N-polar InGaN∕GaN multiquantum wells (MQWs) grown by metal-organic chemical vapor deposition were investigated. Samples grown under optimized conditions exhibited distinct quantum well related emission, smooth surfaces, and abrupt interfaces as evaluated by room temperature photoluminescence, atomic force microscopy, and x-ray diffraction. Enhanced incorporation of indium into N-polar compared to Ga-polar MQW samples was observed for MQWs simultaneously deposited onto the (0001) and (0001¯) GaN-on-sapphire base layers using trimethylindium-to-trimethylgallium-flow-ratios larger than 1.2 during growth. Necessary adjustments of the growth procedure for N polar in comparison with Ga-polar MQWs are described.