AI 中文总结
本研究采用同步辐射X射线衍射结合递归动力学衍射与模拟退火，量化MBE生长的203层QBM器件的结构无序，发现AlGaAs势垒层厚度偏差并为MBE校准提供反馈。
AI 中文摘要
通过分子束外延（MBE）生长的AlGaAs/GaAs超晶格是高级光电器件的基础，包括量子布拉格反射镜（QBM）红外探测器。这些器件的性能关键取决于实现近乎完美的周期性和陡峭的界面，然而MBE生长过程中的固有统计波动会引入纳米级结构无序，可能降低器件效率。本研究提出了一种用于量化203层QBM器件中此类无序的综合方法，采用高能（25 keV）同步辐射X射线衍射进行高分辨率结构表征。通过将递归动力学衍射形式与集成模拟退火精修相结合，我们提取了统计上稳健的逐层厚度分布。分析显示存在高度系统的、材料特有的与标称设计的偏差：所有AlGaAs势垒层均比标称值薄0.3-0.6 nm；此外，连续厚度分布成功识别出最终宏观顶接触层存在35 nm的缺失，以及第一层GaAs层存在40 nm的缺失。这种非破坏性诊断方法达到约0.2至0.6 nm（约1-2个原子单层）的统计精度，为MBE通量校准协议提供了可直接实施的反馈。
英文摘要
AlGaAs/GaAs superlattices grown by Molecular Beam Epitaxy (MBE) are foundational for advanced optoelectronic devices, including Quantum Bragg Mirror (QBM) infrared detectors. The performance of these devices critically depends on achieving near-perfect periodicity and abrupt interfaces, however, intrinsic statistical fluctuations during MBE growth introduce nanoscale structural disorder that can degrade device efficiency. In this study, we present a comprehensive methodology for quantifying this disorder in a 203-layer QBM device. High-resolution structural characterization was performed using high-energy (25 keV) synchrotron X-ray diffraction. By coupling a recursive dynamical diffraction formalism with an ensemble simulated annealing refinement, we extracted statistically robust, layer-by-layer thickness profiles. Our analysis reveals highly systematic, material-specific deviations from the nominal design: all AlGaAs barrier layers were consistently thinner than nominal by 0.3-0.6 nm. Furthermore, the sequential thickness profile successfully identified a significant 35 nm deficit in the final macroscopic top contact layer and a 40 nm deficit in the first GaAs layer. Achieving a statistical precision of about 0.2 to 0.6 nm (approximately 1-2 atomic monolayers), this non-destructive diagnostic approach provides directly actionable feedback for MBE flux calibration protocols.
