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HL: Fachverband Halbleiterphysik

HL 83: Focus Session: III-Nitride Heterostructures for Optoelectronics - Polarization Reduction, Green Gap and High In-containing Alloys

HL 83.6: Topical Talk

Donnerstag, 29. März 2012, 17:45–18:15, EW 201

What causes the efficiency droop in GaN-based LEDs ? — •Joachim Piprek — NUSOD Institute, Newark, DE 19714-7204, USA

GaN-based light-emitting diodes (LEDs) suffer from a reduction (droop) of the quantum efficiency with higher injection current. This droop phenomenon is subject to intense research worldwide, as it delays general lighting applications of GaN-based LEDs. Many proposals have been published in recent years to explain the efficiency droop, but none is generally accepted today. Among the proposed droop mechanisms are enhanced Auger recombination, reduced hole injection, and density-activated Shockley-Read-Hall recombination within the quantum wells. However, different sample preparation and measurement conditions as well as the application of different mathematical models and material parameters lead to a confusing and sometimes contradicting variety of efficiency droop observations and explanations. This talk reviews and contextualizes different droop models within a simple framework and it intends to bring more clarity to the ongoing droop discussion.