Stimulated Emission in InGaN/GaN Multiple Quantum Wells with Different Indium Content

Abstract

We report on high-excitation luminescence spectroscopy of In x Ga 1−x N/GaN multiple quantum wells with a high indium content (x = 0.22 ÷ 0.30). High excitation conditions enabled us to achieve screening of built-in field by free carriers. This allowed for the evaluation of the influence of the band potential fluctuations due to variation in In-content on optical properties. Enhanced spontaneous emission was found for x ≥ 0.22 due to carrier localization within the chaotic band potential. Meanwhile the stimulated emission was found to be the highest for structures with x ≈ 0.25−0.27. We attribute the In-content dependence of the stimulated emission intensity to a trade-off between an increased carrier density and a decrease in the density of states.