X-ray Physics and Heteroepitaxy

本项目致力于完美晶体基底外延生长的表面x射线散射研究。部分工作将致力于将动态衍射理论的精确结果扩展到表面衍射，以补充目前基于运动学理论的描述。使用三晶衍射（TCD）方法在超高真空条件下对干净的硅和锗表面进行测量。然后，实验将继续在锗表面外延生长晶格匹配的碱卤化物的单层覆盖物，使用TCD和x射线驻波（XSW）测量来解决“相位问题”。研究还将扩展到更厚的碱卤化物层，部分是为了监测XSW和TCD光谱中衬底和层上衍射之间的干扰。这种反射高能电子衍射振荡的x射线模拟将用适当的计算模型进行理论分析。

This project is devoted to surface x-ray scattering studies of epitaxial growth onto perfect crystal substrates. Part of the effort will be devoted to an extension of exact results of dynamical diffraction theory to surface diffraction, to complement current descriptions based on kinematical theory. Measurements will be made on clean silicon and germanium surfaces in ultra-high vacuum using the triple crystal diffraction (TCD) method. Experiments will then proceed with monolayer coverages of lattice- matched alkali halides epitaxially grown onto Ge surfaces, with both TCD and x-ray standing wave (XSW) measurements being used to solve the "phase problem." The studies will also be extended to thicker layers of alkali halides, in part to monitor the interference between the substrate and overlayer diffraction in the XSW and TCD spectra. This x-ray analog of reflection high energy electron diffraction oscillations will be analyzed theoretically using appropriate computational models.