Selective-area growth of GaN on non- and semi-polar bulk GaN substrates
We carried out the selective-area growth of GaN and fabricated InGaN/GaN MQWs on non- and semi-polar bulk GaN substrates by MOVPE. The differences in the GaN structures and the In incorporation of InGaN/GaN MQWs grown on non- and semi-polar GaN substrates were investigated. In the case of selective-area growth, different GaN structures were obtained on GaN, GaN, and GaN substrates. A repeating pattern of and facets appeared on GaN. Then, we fabricated InGaN/GaN MQWs on the facet structures on GaN. The emission properties characterized by cathodoluminescence were different for and facets. On the other hand, for InGaN/GaN MQWs on non- and semi-polar GaN substrates, steps along the a-axis were observed by AFM. In particular on GaN, undulations and undulation bunching appeared. Photoluminescence characterization indicated that In incorporation increased with the off-angle from the m-plane and also depended on the polarity.