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Keywords:

  • InGaN LEDs;
  • efficiency droop;
  • leakage;
  • carrier delocalization

Abstract

A temperature dependent investigation into the efficiency droop effect in blue and green InGaN light-emitting diodes (LEDs) is presented. The efficiency droop effect is observed to be the strongest at low temperatures in both blue and green LEDs. We show such behaviour is consistent with a reduced hole injection rate resulting in an increased concentration of electron leakage from the quantum wells. Spectral measurements demonstrate that the emission peak has an “s-shape” dependence on tem-perature and a full-width at half-maximum which increases with decreasing temperature below 100 K. Such observations indicate the importance of carrier localization in the InGaN LEDs. At temperatures where hole injection is not problematic the efficiency droop is the result of carrier delocalization and subsequent defect related recombination with increasing current injection. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)