Micro-photoluminescence mapping of localized luminescent centers in blue and green InGaN/GaN multiple quantum wells

The micro-photoluminescence (PL) of blue and green InGaN/GaN multiple quantum wells (MQWs) grown on sapphire substrates was measured by using laser scanning confocal microscopy (LSCM). In particular, peak energy and linewidth mappings were performed on the MQWs in order to evaluate the influence of the In mole fraction. Double scale potentials were clearly resolved in both MQWs, though nanoscopic potential fluctuations became more significant in the green InGaN/GaN MQWs, which was confirmed via correlations between the PL peak energy and linewidth.