Effect of p-AlGaN electron blocking layers on the injection and radiative efficiencies in InGaN/GaN light emitting diodes

The effect of electron blocking layer (EBL) on the injection and radiative efficiencies in InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) was investigated. In order to identify the dominant mechanism, we measured the external quantum efficiency (EQE), radiative efficiency (RE) and carrier injection efficiency (CIE) experimentally. Through these methods, the origin of efficiency droop and the effect of the EBL were clarified. In addition, the RE and the CIE can be separated quantitatively through our analysis. The insertion of the EBL does reduce the carrier leakage but the RE is also reduced by the insertion, which results in not a significant change in the EQE. The measured piezoelectric field of the QWs significantly increased by the insertion of the EBL, which implies that the insertion of AlGaN layer make a strong effect on the QW strain.