How to decide between competing efficiency droop models for GaN-based light-emitting diodes

GaN-based light-emitting diodes (LEDs) exhibit a strong efficiency droop with higher current injection, which has been mainly attributed to Auger recombination and electron leakage, respectively. Thus far, the few reports on direct measurements of these two processes do not confirm their dominating influence on the droop unambiguously. Advanced numerical simulations of experimental characteristics are shown to validate one or the other explanation by variation of uncertain material parameters. We finally demonstrate how the comparative simulation of temperature effects enables a clear distinction between both models. Contrary to common assumptions, the consistently measured efficiency reduction of blue LEDs with higher ambient temperature eliminates electron leakage as primary cause of the efficiency droop in these devices. (C) 2015 AIP Publishing LLC.