Quantum-well-resolved evaluation of recombination kinetics in InGaN multiple quantum wells: An insight into the role of luminescence enhancement in InGaN underlayer systems

A quantitative understanding of radiative and nonradiative recombination processes is essential for improving both the emission performance and simulation accuracy of nitride-based optical devices. In this study, we applied an integrated characterization scheme combining simultaneous photoacoustic-photoluminescence measurements with time-resolved photoluminescence measurement to InGaN single- and multiple-quantum well (SQW and MQW) structures. By using the SQW and double-QW results as reference data and deconvolving the MQW responses, we obtained QW-resolved internal quantum efficiency (IQE) and photoluminescence (PL) lifetime values in a triple-QW (TQW) sample. Applying a previously developed procedure that relates absolute IQE and PL lifetime further enabled the extraction of radiative and nonradiative recombination lifetimes for each QW. Comparison between the TQW and the SQW sample grown on an InGaN underlayer (SQW-with-UL) yields a consistent physical picture: the uppermost QW in the TQW structure and the SQW-with-UL both exhibit shorter radiative lifetimes and longer nonradiative lifetimes than QWs grown directly on GaN. These QW-resolved lifetimes suggest concurrent contributions from a reduction in defects, compressive strain, and compositional inhomogeneity in InGaN QWs. While the quantitative values are sample-dependent, the methodology demonstrated here provides a general and powerful framework for QW-resolved recombination analysis in InGaN MQW structures and offers insights that support more accurate device modeling and design.