Influences of multiquantum barriers on carrier recombination in InGaN/GaN multiple-quantum-well light-emitting diodes

The influences of multiquantum barriers (MQBs) on the carrier confinement and carrier recombination in blue InGaN/GaN multiple-quantum-well (MQW) light-emitting diodes (LEDs) have been investigated in depth over a broad range of temperatures from 20 to 300K. Time-resolved photoluminescence (TRPL) temporal decay was measured to examine the dynamics of the carriers in both devices. The exciton recombination times of the blue emission are 2.81 and 4.11 ns for the QWs with MQB and GaN barriers, respectively. The former is a reasonable value for the radiative recombination in the structure with MQBs, and results from the enhancement of the exciton confinement. It was found that a device with an MQB structure exhibited higher emission intensity as well as lower temperature sensitivity than the conventional MQW LEDs. The improvement of the quantum efficiency for the MQB device was attributed to the fact that the enhancement of the excitons was confined in the MQW region and inhibited the carrier overflow into the GaN region.