Effect of multiquantum barriers on performance of InGaN∕GaN multiple-quantum-well light-emitting diodes

Abstract

In this paper we demonstrate that the improvement in the emission intensity afforded by the introduction of multiquantum barrier (MQB) structures in an InGaN∕GaN multiple-quantum-well (MQW) light-emitting diode (LED) is attributable to increased excitation cross sections. Over the temperature range from 300to20K, the excitation cross sections of the MQW emissions possessing MQB structures were between 9.6×10−12 and 5.3×10−15cm2, while those possessing GaN barriers were between 8.1×10−12 and 4.5×10−15cm2. We found, however, that the figure of merit for the LED light output was the capture fraction of the cross section; we observed that the dependence of the optical intensity on the temperature coincided with the evolution of the capture fraction. This analysis permitted us to assign the capture cross-section ratios at room temperature for the MQWs with MQBs and with GaN barriers as 0.46 and 0.35. Furthermore, the MQW system possessing well-designed MQB structures not only exhibited the thermally insensitive luminescence but also inhibited energetic carrier overflow.