Defect recombination induced by density-activated carrier diffusion in nonpolar InGaN quantum wells

TL;DR

This study investigates how high excitation densities cause defect-related emission in nonpolar InGaN quantum wells due to carrier diffusion, providing insights into efficiency droop in LEDs.

Contribution

It reveals the mechanism of density-activated defect recombination in nonpolar InGaN quantum wells, linking carrier diffusion to efficiency loss in LEDs.

Findings

Defect emission emerges at high excitation densities.

Bandedge emission efficiency decreases with increasing excitation.

Carrier diffusion from localized to defect states explains the observed phenomena.

Abstract

We report on the observation of carrier-diffusion-induced defect emission at high excitation density in a-plane InGaN single quantum wells. When increasing excitation density in a relatively high regime, we observed the emergence of defect-related emission together with a significant reduction in bandedge emission efficiency. The experimental results can be well explained with the density-activated carrier diffusion from localized states to defect states. Such a scenario of density-activated defect recombination, as confirmed by the dependences of photoluminescence on the excitation photon energy and temperature, is a plausible origin of efficiency droop in a-plane InGaN quantum-well light-emitting diodes.