The present study focuses on a growth strategy to achieve a uniform (and larger) dot size distribution in a multi-stack InAs/InGaAs sub-monolayer (SML) quantum dot (QD) heterostructure by capping with a varying In_xGa_1-xAs (x = 0.15) layer thickness (Y). The In_xGa_1-xAs layer serves both as matrix medium for the dot growth and strain - reducing layer (SRL) to preserve the QD morphology from decomposition. The dots capped by an optimum SRL or capping layer (CL) thickness will alleviate from dot segregation or intermixing, surface diffusion and dot inhomogeneity effects, thus paving way to grow a nearly defect - free quantum dot heterostructure. The experimental calculations on low – temperature (19 K), high – excitation power (1.1 kW/cm²) photoluminescence (PL) revealed ground – state (GS) emission energies at 1.12, 1.14, 1.09 eV for 2, 4, and 6 ML SRL thickness respectively. While, the presence of QD excited state (ES) transitions has been analysed using PL - excitation (PLE) spectroscopy, as the CL will highly alter the band offsets as well as strain inside QDs. The interfacial structural quality, strain relaxation in QDs due to SRL was inspected through high-resolution X – ray diffraction (HRXRD) and Raman measurements. The self – consistent Schrodinger – Poisson solver based on 8 – band k.p formulation was used to evaluate the PL energy and strain profile as a comparison to experimental data. Hence, the sample containing 2 ML CL thickness showed superior results in terms of PL emission and strain, which leads towards the growth of uniform QDs for photodetector (PD) applications operating in the short – wave infrared (SWIR) regime (λ: 0.9 μm–2.5 μm, Energy: 1.377 eV - 0.495eV).

本研究的重点是通过用变化的In _x Ga _1-x覆盖来实现多堆叠InAs / InGaAs亚单层（SML）量子点（QD）异质结构中均匀（且更大）的点尺寸分布的生长策略。层厚度（Y）为（x = 0.15）。In _x Ga _1-x As层既用作点生长的基质介质，又用作应变减小层（SRL），以保护QD形态免于分解。用最佳SRL或覆盖层（CL）厚度覆盖的点将缓解点分离或混合，表面扩散和点不均匀性的影响，从而为生长几乎无缺陷的量子点异质结构铺平了道路。低温（19 K），高激发功率（1.1 kW / cm）的实验计算²）对于2、4和6 ML SRL厚度，光致发光（PL）显示的基态（GS）发射能量分别为1.12、1.14、1.09 eV。同时，已经使用PL-激发（PLE）光谱分析了QD激发态（ES）跃迁的存在，因为CL会极大地改变QD内部的谱带偏移和应变。通过高分辨率X射线衍射（HRXRD）和拉曼测量，检查了界面结构质量，QD引起的量子点应变松弛。基于8频段kp的自一致Schrodinger-Poisson求解器配方被用来评估PL能量和应变曲线，以与实验数据进行比较。因此，包含2 ML CL厚度的样品在PL发射和应变方面显示出优异的结果，这导致了在短波红外（SWIR）体制下工作的光电探测器（PD）应用中均匀QD的增长（λ：0.9μm –2.5μm，能量：1.377 eV-0.495eV）。