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Open AccessArticle

Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well

by Yongbing Zhao 1 and Panpan Li 2,*
1
School of Physics and Electronics, Yancheng Teachers University, Yancheng 224007, China
2
Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93117, USA
*
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(15), 3004; https://doi.org/10.3390/app9153004
Received: 2 July 2019 / Revised: 17 July 2019 / Accepted: 19 July 2019 / Published: 26 July 2019
(This article belongs to the Special Issue Internal Quantum Efficiency of III-Nitride Light-Emitting Diodes)
We demonstrate an ultra-low efficiency droop in c-plane polar InGaN blue light-emitting diodes (LEDs) by reducing the carrier density using a wide InGaN last quantum well (LQW). It is found that the LEDs with a 5.2 nm thick LQW show a negligible efficiency droop, with an external quantum efficiency (EQE) reducing from a peak value of 38.8% to 36.4% at 100 A/cm2 and the onset-droop current density is raised from 3 A/cm2 to 40 A/cm2 as the LQW thickness increases from 3.0 nm to 5.2 nm. The analysis based on the ABC model indicates that small efficiency droop is caused by the reduced carrier density using a wide LQW. The peak efficiency is reduced with a wide LQW, which is caused by the reduction of the electron-hole wavefunction overlap and the deterioration of the crystal quality of the InGaN layer. This study suggests that the application of the InGaN LEDs with a wide LQW can be a promising and simple remedy for achieving high efficiency at a high current density. View Full-Text
Keywords: InGaN; light-emitting diodes; efficiency droop; carrier recombination; carrier localization InGaN; light-emitting diodes; efficiency droop; carrier recombination; carrier localization
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Zhao, Y.; Li, P. Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well. Appl. Sci. 2019, 9, 3004.

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