Threading dislocation density effect on the electrical and optical properties of InGaN light-emitting diodes

The electrical and optical properties of InGaN LEDs with different threading dislocation densities (TDDs) were investigated. LEDs with low TDDs exhibited low forward voltage and high injection efficiency compared with LEDs with high TDDs. The effect of TDDs on the electrical properties of InGaN LEDs was attributed to efficient carrier injection into the QWs brought about by increased transverse carrier mobility in the InGaN layer resulting from reductions in carrier scattering around dislocation cores. In terms of optical properties, LEDs with low TDDs exhibited high peak efficiency and substantial efficiency droops under increased current densities, whereas LEDs with high TDDs showed low peak efficiency and minimal droops under the same condition. These trends can be explained by the correlations of high TDDs with increased dominance of nonradiative recombination and pronounced suppression of peak efficiency under low current densities.