Epitaxial Growth of Uniaxially and Biaxially Mismatched Silicide Films on Silicon

这个项目的目标是更好地理解当覆盖层和衬底之间的失配是各向异性时应变层的外延生长。重点研究了稀土硅化物在硅(001)表面的外延生长。稀土硅化物是理想的测试系统，因为它们相对于Si(001)衬底提供了广泛的各向异性和各向同性失配。形成的硅化物相之间的结构和成分的相似性，以及通过明智地选择稀土金属来改变硅化物晶格常数的能力，为在其他参数如表面能保持不变的情况下，研究外延生长薄膜中作为双轴和单轴晶格失配的函数的生长行为提供了独特的机会。这些系统的另一个特点是硅化物纳米线在生长的初始阶段形成。因此，这项研究还将测试已提出的不同纳米线形成机制在不同材料体系中的相对重要性。这些问题与应变层外延的一般理解有关，并将这种理解具体扩展到应变是各向异性的情况。这项研究的结果也可能有助于开发生长质量更好的纳米线和一般质量更好的金属硅化物薄膜的方法。这个项目解决了材料科学的一个具有重大技术意义的主题领域的基础研究问题。该项目的一个重要特点是培训研究生作为研究人员，掌握几种不同的原子分辨率表征技术。制作的大部分数据将是可视的，这使得它特别适合向对科学和工程有普遍兴趣的广泛年龄段的人展示。将编写材料并将其纳入各种场所的宣传和教育活动中，目的是让尽可能广泛的公众了解材料的基础研究及其与科学知识和未来技术应用的相关性。

The goal of this project is greater understanding of epitaxial growth of strained layers when the mismatch between overlayer and substrate is anisotropic. Focus is on the epitaxial growth of rare earth silicides on the silicon (001) surface. Rare earth silicides are ideal test systems, since they provide a wide range of both anisotropic and isotropic mismatches with respect to the Si(001) substrate. The structural and compositional similarity between the silicide phases formed, and the ability to vary the silicide lattice constants by judicious choice of rare earth metal, provide a unique opportunity to study growth behavior as a function of both biaxial and uniaxial lattice mismatch in epitaxially grown films, with other parameters such as surface energy held constant. Another feature in these systems is the fact that silicide nanowires form in the initial stages of growth. Therefore, the research will also test the relative importance of different mechanisms that have been proposed for nanowire formation in diverse materials systems. These issues have rele-vance to the general understanding of strained layer epitaxy, and the specific extension of this understanding to cases where the strain is anisotropic. The results of this research may also help develop ways of growing both better quality nanowires, and better quality metal silicide films in general. %%% This project addresses basic research issues in a topical area of materials science with significant technological relevance. An important feature of the project is the training of graduate students as researchers with skills in several different atomic resolution characterization techniques. Much of the data produced will be visual in nature, which makes it particularly suitable for presentation to a wide range of age groups with a general interest in science and engineering. Material will be developed and integrated into outreach and educational activities in a variety of venues, with the goal of informing the widest possible public about basic research in materials and its relevance to both scientific knowledge and future technological applications.***