Photoluminescence (PL) measurements at a wide temperature range, up to room temperature, for high-quality and high-density GaAs/AlGaAs quantum dots (QDs) fabricated by droplet epitaxy were carried out to investigate the anomalous temperature dependence of the PL peak energy from the QD ensemble. In addition to a reported redshift that deviated from the so-called Varshni's curve of the PL peak energy in the low temperature region, a new blueshift was observed above 200 K. We analyzed the experimental results using a steady-state rate equation model and observed a good agreement. The distribution of the QD sizes and the presence of the AlGaAs barrier layer as a carrier coupling channel were considered in this model. This means that the wetting layer proposed thus far is not a necessary condition for explaining the anomalous temperature behavior of the PL properties. In addition, it was found that the anomalous temperature behavior was smeared out by the insertion of a GaAs height adjustment layer in order to homogenize the apparent QD size. We found that sufficient control of the QD size is a necessary factor for high temperature stability of QD devices.

中文翻译：

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AlGaAs 势垒层作为光激发载流子再分布通道的有效性对 GaAs 量子点光致发光特性的反常温度依赖性

对通过液滴外延制造的高质量和高密度 GaAs/AlGaAs 量子点 (QD) 在很宽的温度范围内（高达室温）进行光致发光 (PL) 测量，以研究 PL 峰值能量的异常温度依赖性来自 QD 系综。除了所报告的偏离低温区域 PL 峰值能量的所谓 Varshni 曲线的红移之外，在 200 K 以上观察到了新的蓝移。 我们使用稳态速率方程模型分析了实验结果并观察到一个很好的协议。在该模型中考虑了 QD 尺寸的分布和作为载流子耦合通道的 AlGaAs 势垒层的存在。这意味着迄今为止提出的润湿层不是解释 PL 特性的异常温度行为的必要条件。此外，发现通过插入 GaAs 高度调整层以均匀化表观 QD 尺寸，异常温度行为被涂抹掉了。我们发现 QD 尺寸的充分控制是 QD 器件高温稳定性的必要因素。