Reduction of efficiency droop in InGaN-based blue LEDs

X. Ni; X. Li; J. Xie; Q. Fan; R. Shimada; Ü. Özgür; H. Morkoç

doi:10.1117/12.809877

16 February 2009 Reduction of efficiency droop in InGaN-based blue LEDs

X. Ni, X. Li, J. Xie, Q. Fan, R. Shimada, Ü. Özgür, H. Morkoç

Proceedings Volume 7216, Gallium Nitride Materials and Devices IV; 72161W (2009) https://doi.org/10.1117/12.809877
Event: SPIE OPTO: Integrated Optoelectronic Devices, 2009, San Jose, California, United States

Abstract

We have investigated the efficiency droop in InGaN based multiple-quantum light-emitting diodes (MQWs-LEDs) and double hetero-structure light-emitting diodes (DH-LEDs) by changing the barrier (both thickness and barrier height) within quantum wells. Our results show that for MQW-LEDs, with the decrease of barrier width from 12nm In_0.01Ga_0.99N to 3nm In_0.01Ga_0.99N, the external quantum efficiency (EQE) droop point is increased from 350 Acm^-2 to >1000 Acm^-2, and the slope of EQE drop is also greatly reduced. When the barrier height of the MQW-LEDs is decreased, i.e. barriers changed from In_0.01Ga_0.99N (3nm) to In_0.06Ga_0.94N (3nm), the EL intensity is reduced to half. In the case of DH-LEDs, 6nm DH-LED shows the highest EL intensity and no EQE droop up to 1000 Acm^-2. When the active region of the DHLED is increased from 6nm to 12nm, the electroluminescence (EL) intensity is reduced to 70% of that of the 6nm DHLED, and the EQE shows negligible droop compared to the 6nm DH-LED due to both enhanced hole injection and reduced electron overflow. These results suggest that heavy effective mass of holes and low hole injection efficiency (due to relatively lower p-doping) leading to severe electron leakage are responsible for the efficiency droop.

Citation Download Citation

X. Ni, X. Li, J. Xie, Q. Fan, R. Shimada, Ü. Özgür, and H. Morkoç "Reduction of efficiency droop in InGaN-based blue LEDs", Proc. SPIE 7216, Gallium Nitride Materials and Devices IV, 72161W (16 February 2009); https://doi.org/10.1117/12.809877

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