Formation and optical properties of GaN/AlN multi-stacks with GaN nano-structures by metallorganic chemical vapour deposition

A 16-pair GaN/AlN structure with GaN nano-structures at the hetero-interface was grown by a metallorganic chemical vapour deposition (MOCVD) system. From the atomic force microscopy (AFM) analysis of the AlN surface grown on the GaN/sapphire template, there are many nano-trenches and nano-holes with a density of about 5 × 108 cm−2. These GaN nano-structures fill the AlN nano-holes with a dimension of 40 × 40 nm2 in width and depth, and with a line density of 6 × 104 cm−1. Furthermore, these GaN nano-structures will be propagated and self-aligned in the growth direction. The photoluminescence (PL) measurement showed that there are bright and dark emission areas on the surface of the 16-pair GaN/AlN structure; the PL intensity at the bright region was ten times stronger than the dark region, and this stronger GaN peak has the blue-shift property caused by a quantum confined effect. In the end, we concluded that the V-shape GaN nano-structures filling the AlN nano-hole structure have a strongly quantum confined effect depending on the temperature and the power dependent PL results.