ABSTRACT
The recent researches referring to InGaN/GaN multiple quantum well light-emitting diodes (MQW LEDs) mainly focused on finding ways to improve the devices’ performance, for the increasing demands in white light illumination and LED displays. Thus, the analysis to their photoluminescence (PL) dynamics became more and more important because these results might reveal the exact recombination mechanism inside these LED devices, which could guide us to design devices with better performance. Based upon these, this chapter reviews the studies of the PL dynamic properties of InGaN/GaN MQW LEDs, with either a typical construction or some improved structures realized in recent years, wherein exciton localization has proved to be the main reason for high-efficiency emission, and at least two different kinds of localization centers—local compositional fluctuations of indium and thickness variation of InGaN layers—existed in the MQW system and contributed to the emission; quantum-confined Stark effect (QCSE) was proven to be the main drawback in conventional 186MQW LEDs. Several strategies to remove or reduce the QCSE, such as introducing charge asymmetric resonance tunneling (CART) structures or pre-strained layers, or the replacement of polar substrates with semipolar/nonpolar substrates had positive effects on the PL efficiencies. A clear picture for the photoluminescence process within InGaN/GaN MQW structure is drawn in this work by combining different kinds of PL results. This penetrative investigation was helpful to further improve the material design and growth of InGaN/GaN MQWs for the wide spectral LED applications.
