Efficient observation of narrow isolated photoluminescence spectra from spatially localized excitons in InGaN quantum wells

We report discrete photoluminescence (PL) spectra with narrow linewidths from spatially localized excitons obtained in InGaN quantum wells (QWs) that are of a similar structure to those used in conventional optical devices. A micro-PL measurement combined with submicrometer-scale fabrication techniques allows us to create a small number of excitons in a laser spot and to detect the PL from single spatially localized excitons. A sharp PL line (linewidth: 0.34 meV limited by the resolution) is clearly obtained in a 0.2 μm mesa-shaped QW, which originates from a single localized exciton. We show that the technique is a more powerful method of examining excitonic effects than previously reported methods.