Carrier Dynamics in UV InGaN Multiple Quantum Well Inverted Hexagonal Pits

The emission and recombination characteristics of UV or blue light emission from InGaN/GaN quantum well (QW) structures influenced by V-shaped pits have been investigated by near-field and time-resolved photoluminescence measurements. Localization of charge carriers due to the potential barriers caused by the V-shaped pit formation is observed to be modified by thermal excitation. Temperature dependence of recombination dynamics shows evidence of a more complex potential barrier produced by the inverted hexagonal pits embedded within the multiple QWs. The emission from the narrow V-shaped pit QWs shows anomalous temperature dependence behavior that is significantly different from the emission from c-plane QWs. The carrier recombination process in c-plane QWs is significantly longer ~ 5 ns compared to the ~ 1.5 ns in V-shaped pit QWs at low temperatures due to the larger piezoelectric fields in wider wells. At room temperature, the recombination lifetimes are comparable due to increased carrier separation and delocalization within the V-shaped pit QWs.