Photomodulated Reflectivity Measurement of Free-Carrier Dynamics in InGaN/GaN Quantum Wells
Photomodulated Reflectivity Measurement of Free-Carrier Dynamics in InGaN/GaN Quantum Wells
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DOI：
10.1021/acsphotonics.8b00904
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发表时间：
2018-10
期刊：
影响因子：
7
通讯作者：
M. Halsall;I. Crowe;J. Mullins;R. Oliver;M. Kappers;C. Humphreys
中科院分区：
文献类型：
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作者：
M. Halsall;I. Crowe;J. Mullins;R. Oliver;M. Kappers;C. Humphreys
我们描述了一种基于光调制反射率（PMR）测量固态光学材料中载流子动力学的新技术，并作为一个例子，将其应用于生长在c面蓝宝石衬底上的InGaN/GaN多量子阱（QW）结构的研究。该技术是频率调制光谱的一种形式，依赖于探测光激发期间自由载流子密度波动引起的折射率变化。我们表明，它是可以准确地确定载流子密度和寿命，独立于任何光致发光（PL）的测量和没有知识的入射，或吸收，激光功率的分数，数量，可以引起相当大的不确定性PL研究。我们表明，这种不确定性可能导致一个数量级的低估的总光生载流子密度和妥协的准确性，在确定载流子寿命。我们确定，通过比较两种技术，PMR和PL，无辐射SH…
We describe a novel technique for measuring carrier dynamics in solid-state optical materials based on photomodulated reflectivity (PMR) and, as an example, apply it to a study of an InGaN/GaN multi-quantum-well (QW) structure grown on a c-plane sapphire substrate. The technique is a form of frequency modulation spectroscopy and relies on probing changes in refractive index induced by fluctuations in free-carrier density during optical excitation. We show that it is possible to accurately determine both carrier density and lifetime, independent of any photoluminescence (PL) measurement and with no knowledge of the incident, or fraction of absorbed, laser power, quantities that can give rise to considerable uncertainties in PL studies. We demonstrate that such uncertainties can lead to an order of magnitude underestimation of the total photogenerated carrier density and compromised accuracy in determining carrier lifetime. We determine, by a comparison of the two techniques, PMR and PL, the nonradiative Sh...