Towards a deeper understanding of the reduced efficiency droop in low defect-density GaInN wide-well LEDs

A series of 400 nm emitting GaInN/GaN single‐well light‐emitting diodes, grown on ultra‐low dislocation density GaN templates with well widths varying between 3 and 18 nm, were investigated by pulsed and time resolved electroluminescence measurements using small signal modulation technique for the latter. A reduction of the efficiency droop at high current densities with increasing well width was observed. The highest overall external quantum efficiency was obtained for LEDs with 11 nm thick double‐heterostructure (or wide well) active region at current densities above 70 A/cm2. Furthermore, carrier lifetime and volume carrier density in the wells were determined. A model based on the interplay between defect assisted recombination, depending on dislocation density, and strongly carrier density dependent loss processes is presented explaining the well‐thickness dependence of the efficiency droop. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)