Analysis of efficiency droop in nitride light-emitting diodes by the reduced effective volume of InGaN active material

In InGaN quantum wells (QWs), effective active volume can be greatly reduced due to carrier localization in In-rich region and inhomogeneous carrier distribution. The authors investigate the efficiency droop of InGaN-based light-emitting diodes (LEDs) based on the carrier rate equation including the influence of the reduced effective active volume. It is found that efficiency droop characteristics can be modeled well without employing a large Auger recombination coefficient by assuming that only a small portion of the QWs is effectively used as active region. The presented model is expected to provide insight into the realization of droop-free operation in nitride LEDs.