Abstract:The authors report an investigation of two wavelength excited photoluminescence on InGaN/GaN multiple quantum wells. It is found that with an addition below-gap excitation the photoluminescence intensity can be quenched by up to 50%. In addition, the decay time of localized carriers changes from 173.9 to 7.9 ns. The experimental results can be well explained in terms of the electronic transitions involving deep defect states in the GaN barrier. Based on the variation of the photon energy of the below-gap excitation, the origin of the deep trap can be identified. The authors point out here that two wavelength excitation spectroscopy is a powerful tool to reveal nonradiative defects in optoelectronic devices.