Observation of robust hot carrier effects in quantum-well structures has prompted hopes to increase the efficiency of solar cells beyond the Shockley–Queisser limit (33% for single junction solar cells at AM1.5G). One of the main studies in hot carrier effects is the determination of carrier temperature, which provides information on the thermalization mechanisms of hot carriers in semiconductor materials. Here, we investigate the spatial distribution of photo-generated hot carriers in a InGaAs multi-quantum-well structure via hyperspectral luminescence imaging. We discuss proper methods of extracting the temperature of carriers from a photoluminescence spectrum. Robust hot carrier effects are observed at the center of the laser spot at various lattice temperatures. In addition, it is seen that the local carrier temperature scales linearly with the local laser intensity as long as the illumination exceeds a threshold power; the carrier temperature at regions with local intensities below the threshold drops to the lattice temperature, i.e., experiences no hot carrier effects. Moreover, at large distances from the concentrated light, where the level of illumination is negligible, evidence of carrier radiative recombination is observed, which is attributed to carrier diffusion in the planar structure. The results of this study can be applied to investigate the influence of carrier diffusion and thermoelectric effects on the thermalization of hot carriers.

中文翻译：

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通过高光谱发光成像研究量子阱结构中热载流子的空间分布

对量子阱结构中强大的热载流子效应的观察促使人们希望将太阳能电池的效率提高到超出肖克利-奎瑟极限（AM1.5G 单结太阳能电池为 33%）。热载流子效应的主要研究之一是载流子温度的确定，这提供了有关半导体材料中热载流子热化机制的信息。在这里，我们通过高光谱发光成像研究了 InGaAs 多量子阱结构中光生热载流子的空间分布。我们讨论了从光致发光光谱中提取载流子温度的正确方法。在不同晶格温度下，在激光光斑的中心观察到强大的热载流子效应。此外，可以看出，只要照明超过阈值功率，局部载流子温度与局部激光强度成线性比例；局部强度低于阈值的区域的载流子温度下降到晶格温度，即没有经历热载流子效应。此外，在距离集中光很远的地方，照明水平可以忽略不计，观察到载流子辐射复合的证据，这归因于平面结构中的载流子扩散。本研究结果可用于研究载流子扩散和热电效应对热载流子热化的影响。局部强度低于阈值的区域的载流子温度下降到晶格温度，即没有经历热载流子效应。此外，在距离集中光很远的地方，照明水平可以忽略不计，观察到载流子辐射复合的证据，这归因于平面结构中的载流子扩散。本研究结果可用于研究载流子扩散和热电效应对热载流子热化的影响。局部强度低于阈值的区域的载流子温度下降到晶格温度，即没有经历热载流子效应。此外，在距离集中光很远的地方，照明水平可以忽略不计，观察到载流子辐射复合的证据，这归因于平面结构中的载流子扩散。本研究结果可用于研究载流子扩散和热电效应对热载流子热化的影响。