Multiple stacking of sub-monolayer (SML) quantum dot (QD) heterostructure exhibits high optical quality and is seen in devices like lasers diodes, photodetectors, etc. In this study, we have investigated the optical and material characterization of InAs/InGaAs SML quantum dot (QD) heterostructure with multiple stacking layers (nSML) on GaAs substrates. The experimentally calculated PL emission energies were found to be 1.19, 1.13, 1.11 and 1.12 eV for 4, 6, 8 and 10 QD stacks at 19 K, excitation power of 1.1 kW/cm2 (25 mW) respectively. A feature of increased strain with increasing nSML was verified experimentally by high-resolution X-ray diffraction (HRXRD) and Raman measurements as well. The experimental PL peak energy data were then validated with nextnano++ simulations based on Schrödinger – Poisson device solver. The hydrostatic and biaxial strain components were computed to correlate the experimental and simulation data. Hence with these enunciated understandings, we conclude that an ideal choice on the number of SML stacks that can be grown on a GaAs substrate was found to be 6 stacks, helpful to realize and fabricate QD based infrared photodetectors (QDIPs) devices in long wavelength regime.

中文翻译：

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分子束外延生长的不同 InAs/InGaAs 亚单层量子点异质结构堆叠的带间和子带间光学跃迁研究

亚单层 (SML) 量子点 (QD) 异质结构的多重堆叠表现出很高的光学质量，在激光二极管、光电探测器等器件中可见。在这项研究中，我们研究了 InAs/InGaAs SML 量子的光学和材料表征GaAs 衬底上具有多个堆叠层 (nSML) 的点 (QD) 异质结构。实验计算的 PL 发射能量分别为 1.19、1.13、1.11 和 1.12 eV，对于 4、6、8 和 10 个 QD 堆栈，在 19 K，激发功率为 1.1 kW/cm2 (25 mW)。随着 nSML 增加，应变增加的特征也通过高分辨率 X 射线衍射 (HRXRD) 和拉曼测量进行了实验验证。然后使用基于薛定谔 - 泊松设备求解器的 nextnano++ 模拟验证实验 PL 峰值能量数据。计算流体静力和双轴应变分量以关联实验和模拟数据。因此，根据这些阐明的理解，我们得出结论，可以在 GaAs 衬底上生长的 SML 堆栈数量的理想选择是 6 个堆栈，有助于实现和制造长波长范围内基于 QD 的红外光电探测器 (QDIP) 器件.