Near-field optical study of InGaN/GaN epitaxial layers and quantum wells

We have employed near-field scanning optical microscopy to investigate the influence of specific microstructural defects on the optical properties of thin InGaN/GaN epilayers and quantum wells. These defects are empty “pinholes” with a hexahedron cone morphology that are nucleated by threading dislocations from the GaN buffer layer. By correlating atomic force microscopy with spatially and spectrally resolved photoluminescence (PL) on a 100 nm spatial scale, we find that the pinholes have no clearly observable effect on the PL efficiency, at least partly due to the strong carrier localization in the InGaN nonrandom alloy.