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Time-resolved and temperature-varied photoluminescence studies of InGaN/GaN multiple quantum well structures

Two comparative blue emitting InGaN/GaN multiple quantum well (MQW) structures, for lighting and laser diode applications, with and without pre-strained layer, were grown by MOCVD. Temperature dependent photoluminescence (TDPL) and time-resolved (TR) PL were used to study their optical and transient properties. PL signals from InGaN MQWs were divided into two parts: one is the band to band transition of InGaN; the other is the broad defect band. It is indicated that the InGaN/GaN MQW structure with prestrained layer has larger activation energy. TRPL measurements were performed in 10-300 K and with the detection wavelength cross over the emission peak. It is found that the MQW sample with prestrained layer has deeper localization depth. Temperature dependence of PL decay time shows an interesting behavior of an increase from 10K to 30K and then a decrease till 300K.