Measurements of light-output power versus current were performed for GaInN/GaN light-emitting diodes grown on GaN-on-sapphire templates with different threading dislocation densities. Low-defect-density devices exhibit a pronounced efficiency peak followed by droop as current increased, whereas high-defect-density devices exhibited low peak efficiencies and little droop. The experimental data were analyzed with a rate equation model to explain this effect. Analysis revealed that dislocations do not strongly impact high-current performance; instead they contributed to increased non-radiative recombination at lower currents and a suppression of peak efficiency. The characteristics of the dominant recombination mechanism at high currents were consistent with processes involving carrier leakage.

Effect of Dislocation Density on Efficiency Droop in GaInN/GaN Light-Emitting Diodes. M.F.Schubert, S.Chhajed, J.K.Kim, E.F.Schubert, D.D.Koleske, M.H.Crawford, S.R.Lee, A.J.Fischer, G.Thaler, M.A.Banas: Applied Physics Letters, 2007, 91[23], 231114