Study on evaluation method for luminescence efficiency and efficiency droop mechanism in III-nitride-based LEDs

利用光致发光（PL）和时间分辨PL谱研究了InGaN合金半导体系统的光学性质。在对InGaN纳米线的内量子效率和复合动力学进行评估的基础上，澄清了估算内量子效率中存在的争议。此外，在分析量子效率与激发功率密度关系的基础上，讨论了高激发条件下效率降低的机理。结果表明，高激发功率密度下量子效率的降低反映了光生激子局域态的饱和。

The optical properties of InGaN alloy semiconductor systems have been studied by means of photoluminescence (PL) and time-resolved PL spectroscopy. On the basis of the evaluation of the internal quantum efficiency (IQE) and recombination dynamics of InGaN nanowires, the controversial issues of the estimation of IQE were clarified. Moreover, the mechanism of efficiency reduction under the higher excitation condition was discussed based on the analysis of the excitation power density dependence of IQE. It was found that the reduction of the IQE under higher excitation power density reflected the saturation of localized states by photo-generated excitons.