Nonradiative recombination dynamics in InGaN/GaN LED defect system

Abstract

Complex investigations, including measurements of C – V curves, studies of I – V curves in the 10 mV–5 V voltage and 10 −14–1 A current ranges and QE(I) dependences, were carried out on the set of InGaN/GaN LEDs with different active region designs, and with different maximum external quantum efficiency (QE), changing from 16% to 40%. Common regularities of carriers transport for all investigated LEDs were found. They were independent of barriers height and width, number of wells and nanostructural arrangement, and can be related to the non-radiative carrier recombination dynamics taking place in the presence of the extended defect system piercing the LED active region. The results obtained allow us to assume that the effect of the extended defect system on QE, is indirect and consists mainly of the electric field redistribution in the active region, as the properties of shunts formed by these defects are changed under the current injection. The point defect effect is the most probably seen in the narrow current range corresponding to the QE maximum. It was assumed that the Auger processes involving recombination centers, localized on the extended defects, could be the cause of quantum efficiency decay at current densities larger than 50 A/cm 2.