Investigation of Efficiency-Droop Mechanisms in Multi-Quantum-Well InGaN/GaN Blue Light-Emitting Diodes

Efficiency-droop mechanisms and related technological remedies are critically analyzed in multi-quantum-well (QW) InGaN/GaN blue light-emitting diodes by means of numerical device simulations and their comparison with experimental data. Auger recombination, electron leakage, and incomplete QW carrier capture can separately produce droop effects in quantitative agreement with experimental data, but "extreme" values, at the limit of or outside their generally accepted range, must be imposed for related droop-controlling parameters. Less stringent conditions are needed if combinations of the aforementioned mechanisms are assumed to act jointly. Applying technological/structural modifications like QW thickness or number increase and barrier p-type doping leads to distinctive effects on droop characteristics depending on the assumed droop mechanism. Increasing the QW number appears, in particular, to be the most effective droop remedy in case the phenomenon is induced by Auger recombination. Possible technology-dependent variation of droop-controlling parameters and/or multiple droop mechanisms can, however, make discrimination of droop origin on the basis of the effects of applied technological remedies very difficult.