Abstract The authors report the optimization of vertically coupled active layers of InAs quantum dots (QDs) grown epitaxially following a unique in-situ growth strategy to achieve controlled strain propagation in subsequent layers resulting in homogenous dot-size distribution. The analysis comprises of bi, tri, penta, hepta and deca coupled layers which have been characterized for their optical properties using photoluminescence spectroscopy (PL) and photoluminescence excitation spectroscopy measurements (PLE) while high resolution X-ray diffraction (HR-XRD) measurements (in-plane and out-of-plane) have been carried out for structural characterization. A gradual shift from bi-modal to monomodal distribution is observed on increasing the coupled layers above five. Activation energies (Ea) calculated from temperature dependent PL results show least thermal quenching for hepta layer coupling which is further corroborated by the strongest room temperature luminescence obtained for the respective sample amongst others. Least out-of-plane compressive strain and also least in-plane tensile strain have been calculated from the HR-XRD results for the hepta layer coupled sample. Furthermore, the in-plane HR-XRD results show minimal amount of In–Ga intermixing for the hepta layer coupling which provides direct evidence of the superior material quality of this heterostructure. Quantum-dot infrared photodetectors (QDIPs) fabricated from the samples have been characterized for their spectral response wherein multiple sharp peaks with narrow full-width at half maxima (FWHM) are obtained in the short-wave infrared (SWIR) region for the hepta layer device, which is absent in other spectra. Also, the response survives up to room temperature (300 K) and stretches in the mid-wave infrared region (MWIR) region (~5 μm). High peak responsivity (Rp = 120.34 A/W) is obtained for the hepta layer device which is much higher than previously reported responsivity values.

中文翻译：

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应用生长策略优化 InAs/GaAs pip 量子点红外光电探测器中的垂直应变耦合

摘要 作者报告了按照独特的原位生长策略外延生长的 InAs 量子点 (QD) 的垂直耦合有源层的优化，以在后续层中实现受控的应变传播，从而产生均匀的点尺寸分布。分析包括bi、tri、penta、hepta和deca耦合层，这些耦合层已使用光致发光光谱（PL）和光致发光激发光谱测量（PLE）以及高分辨率X射线衍射（HR-XRD）测量表征其光学特性（平面内和平面外）已用于结构表征。在将耦合层增加到五个以上时，观察到从双峰分布到单峰分布的逐渐转变。从温度相关的 PL 结果计算的活化能 (Ea) 显示七层耦合的热猝灭最少，这进一步被各个样品获得的最强室温发光进一步证实。从七层耦合样品的 HR-XRD 结果计算出最小的面外压缩应变和最小的面内拉伸应变。此外，面内 HR-XRD 结果显示七层耦合的 In-Ga 混合量最小，这直接证明了这种异质结构的优异材料质量。由样品制成的量子点红外光电探测器 (QDIP) 的光谱响应已被表征，其中在七层的短波红外 (SWIR) 区域获得了多个具有窄半峰全宽 (FWHM) 的尖峰设备，这是其他光谱中不存在的。此外，响应在室温 (300 K) 下仍然存在，并在中波红外区域 (MWIR) 区域 (~5 μm) 中延伸。七层器件获得了高峰值响应率 (Rp = 120.34 A/W)，远高于先前报告的响应率值。