Impact of ammonia flow rate on nonradiative recombination centers and localized states grown in InGaN multiquantum wells

In this article, we focus on the impact of ammonia flow rate during metal-organic chemical vapor deposition growth on the luminescence characteristics of InGaN multiple quantum wells (MQWs). By analyzing the electroluminescence spectra, temperature-dependent photoluminescence, and fluorescent microscopy images of MQW light-emitting diodes, we established the influence of ammonia flow rate on nonradiative recombination centers and localized states appearing on the surface and inside quantum wells. It was found that the ammonia flow rate affects the distribution of localized states in the bulk of quantum wells, reducing the FWHM of luminescence peaks. In addition, increasing the ammonia flow rate promotes the surface decomposition of InGaN films and decreases growth rate, weakening the quantum-confined Stark effect and improving surface quality. But it also makes injected carriers more susceptible to be captured by nonradiative recombination centers, which may reduce luminescence efficiency.