Efficiency droop in light‐emitting diodes: Challenges and countermeasures
TLDR
In this article, the authors present a theoretical model for the carrier leakage caused by the asymmetry of the pn junction, specifically the disparity between electron and hole concentrations and mobilities.Abstract:
Efficiency droop, i.e. the loss of efficiency at high operating current, afflicts nitride-based light-emitting diodes (LEDs). The droop phenomenon is currently the subject of intense research, as it retards the advancement of solid-state lighting which is just starting to supplant fluorescent as well as incandescent lighting. Although the technical community does not yet have consented to a single cause of droop, this article provides a summary of the present state of droop research, reviews currently discussed droop mechanisms, and presents a recently developed theoretical model for the efficiency droop. In the theoretical model, carrier leakage out of the active region caused by the asymmetry of the pn junction, specifically the disparity between electron and hole concentrations and mobilities, is discussed in detail. The model is in agreement with the droop's key behaviors not only for GaInN LEDs but also for AlGaInP LEDs.read more
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References
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Enhancement in hole-injection efficiency of blue InGaN light-emitting diodes from reduced polarization by some specific designs for the electron blocking layer
TL;DR: Simulation results show that polarization-induced downward band bending is mitigated in these redesigned EBLs and, hence, the hole injection efficiency increases markedly and the optical performance and efficiency droop are improved, especially under the situation of high current injection.
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Yunyan Zhang,Yi An Yin +1 more
TL;DR: In this paper, the characteristics of the nitride-based blue light-emitting diode (LED) with an AlGaN/GaN superlattice (SL) electron blocking layer (EBL) of gradual Al mole fraction are analyzed numerically and experimentally.
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Hole transport improvement in InGaN/GaN light-emitting diodes by graded-composition multiple quantum barriers
Chi-Luen Wang,Shu-Hsiu Chang,Shu-Hsiu Chang,P. H. Ku,Jinchai Li,Yu-Pin Lan,Chien-Chung Lin,H. C. Yang,Hao-Chung Kuo,Tien-Chang Lu,S. C. Wang,Chun-Yen Chang +11 more
TL;DR: In this article, a graded-composition multiple quantum barriers (GQB) was incorporated in c-plane InGaN/GaN light-emitting diodes (LEDs) grown on a cplane sapphire substrate to improve hole transport and efficiency.
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On the origin of IQE‐‘droop’ in InGaN LEDs
Ansgar Laubsch,Matthias Sabathil,Werner Bergbauer,Martin Strassburg,Hans Lugauer,Matthias Peter,Stephan Lutgen,Norbert Linder,Klaus Streubel,Jörg Hader,Jerome V. Moloney,Bernhard Pasenow,Stephan W. Koch +12 more
TL;DR: In this article, the authors identify a quantum well internal high density Auger-like loss process as the origin of the so-called "droop" of internal quantum efficiency (IQE) in InGaN based light emitters.
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Asymmetry of carrier transport leading to efficiency droop in GaInN based light-emitting diodes
David S. Meyaard,Guan-Bo Lin,Qifeng Shan,Jaehee Cho,E. Fred Schubert,Hyun Wook Shim,Min-Ho Kim,Cheol-soo Sone +7 more
TL;DR: In this paper, the effect of the asymmetry in carrier concentration and mobility in GaInN pn-junction light-emitting diodes (LEDs) is studied.