Carrier Density Dependent Localization and Consequences for Efficiency Droop in InGaN/GaN Quantum Well Structures
Carrier Density Dependent Localization and Consequences for Efficiency Droop in InGaN/GaN Quantum Well Structures
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DOI：
10.7567/jjap.52.08jk10
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发表时间：
2013-08
影响因子：
1.5
通讯作者：
T. Badcock;S. Hammersley;D. Watson‐Parris;P. Dawson;M. J. Godfrey;M. Kappers;C. McAleese;R. Oliver;C. Humphreys
中科院分区：
文献类型：
--
作者：
T. Badcock;S. Hammersley;D. Watson‐Parris;P. Dawson;M. J. Godfrey;M. Kappers;C. McAleese;R. Oliver;C. Humphreys
我们报告的观察减少的深度的S-形状的光致发光峰值能量的温度依赖性随着激发功率密度的增加。在S形深度减小的激发功率密度范围内，我们还观察到每单位激发功率的积分光致发光强度减小，即，效率下降。因此，效率下降的开始发生在与载流子离域的开始相同的载流子密度处。我们将这些实验结果与理论模型的预测的载流子本地化的影响，由于在InGaN/GaN量子威尔斯的光学性质上的随机分布的In原子的浓度的局部变化。在此基础上的理论与实验的比较，我们属性的S形温度依赖性的饱和可用的局域态的减少。我们建议，这种饱和的本地化状态是一个促成因素的效率下降，从而非本地化的载流子重组非辐射。
We report on the observation of a reduction in the depth of the S-shape in the temperature dependence of the photoluminescence peak energy with increasing excitation power density. Over the range of excitation power density where the depth of the S-shape is reduced, we also observe a reduction in the integrated photoluminescence intensity per unit excitation power, i.e., efficiency droop. Hence, the onset of efficiency droop occurs at the same carrier density as the onset of carrier delocalization. We correlate these experimental results with the predictions of a theoretical model of the effects of carrier localization due to local variations in the concentration of the randomly distributed In atoms on the optical properties of InGaN/GaN quantum wells. On the basis of this comparison of theory with experiment we attribute the reduction in the S-shape temperature dependence to the saturation of the available localized states. We propose that this saturation of the localized states is a contributory factor to efficiency droop whereby nonlocalized carriers recombine non-radiatively.