A laboratory in situ grazing-incidence small-angle X-ray scattering (GISAXS) tracking of the self-assembled growth of a regular 3D Ge quantum dot (QD) structure in an amorphous Al2O3 matrix during the ion beam sputter deposition of a periodic Ge/Al2O3 multilayer on silicon is reported. A 573 K substrate temperature proved to be necessary to achieve the self-assembly effect. Relying on a fast repeated acquisition of GISAXS patterns, the temporal evolution of the growing 3D Ge QD structure was analyzed bilayer by bilayer to determine its type, lateral and vertical correlation lengths, and inter-QD distance. The QD structure was found to have body-centered tetragonal lattice type with ABA stacking, with the lattice parameters refined by fitting the final GISAXS pattern relying on a paracrystal model. A single set of paracrystal parameters enables one to simulate the temporal evolution of the in situ GISAXS patterns throughout the deposition process, suggesting that the Ge QD self-assembly is driven from the very beginning solely by the growing surface morphology. Ex situ GISAXS and X-ray reflectivity measurements along with a cross-section high-resolution transmission electron microscopy analysis complete the study.

中文翻译：

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实时跟踪氧化铝基质中 3D Ge 量子点晶格的自组装生长

实验室原位掠入射小角 X 射线散射 (GISAXS) 跟踪在周期性 Ge 的离子束溅射沉积期间非晶 Al2O3 基质中规则 3D Ge 量子点 (QD) 结构的自组装生长报道了硅上的 /Al2O3 多层膜。573 K 的衬底温度被证明是实现自组装效果所必需的。依靠对 GISAXS 模式的快速重复获取，逐层分析了不断增长的 3D Ge QD 结构的时间演变，以确定其类型、横向和垂直相关长度以及 QD 间距离。发现 QD 结构具有带有 ABA 堆叠的体心四方晶格类型，晶格参数通过依赖于副晶体模型拟合最终 GISAXS 图案来细化。一组副晶体参数使人们能够模拟整个沉积过程中原位 GISAXS 图案的时间演变，这表明 Ge QD 自组装从一开始就完全由生长的表面形态驱动。异地 GISAXS 和 X 射线反射率测量以及横截面高分辨率透射电子显微镜分析完成了这项研究。