Rare earth modified silicon surfaces as templates for organic layer growth

薄的有机层在硅表面上的有序生长是目前的高度兴趣，因为它们迷人的物理性质，以及在考虑到可能的应用，包括有机物集成到硅技术。然而，纯硅表面是高度反应性的，因为它们的不饱和悬挂键，通常导致相当无序的有机膜。一个有趣的替代方案是硅表面改性的薄层原子，如氢，硼，或金属原子，这已被深入研究。最近，我们首次观察到，Si（111）表面覆盖的稀土硅化物单层是一个有前途的模板高度有序的有机薄膜的生长，在这种情况下的钴酞菁分子。在本项目中，我们计划对沉积在这些稀土改性硅表面上的选定有机分子进行详细研究，以确定薄膜的原子结构和形态，有序生长的机制及其电子和化学性质。为此，我们采用扫描隧道显微镜和光谱，低能电子衍射，光电子能谱，和近边X射线吸收精细结构光谱。通过选择具有不同结构和潜在反应位点的不同特征的分子，我们可以改变较小的局部范德华相互作用和局部化学键合之间的平衡，以调节分子的流动性及其形成有序层的趋势。

The ordered growth of thin organic layers on silicon surfaces is currently of high interest because of their fascinating physical properties as well as in view of possible applications including the integration of organics into the silicon technology. However, pure silicon surfaces are highly reactive because of their unsaturated dangling bonds, usually leading to rather disordered organic films. An interesting alternative are silicon surfaces modified by thin layers of atoms such as hydrogen, boron, or metal atoms, which have been studied intensively. Recently, we observed for the first time that Si(111) surfaces covered by rare earth silicide monolayers are a promising template for the highly ordered growth of thin organic films, in this case of cobalt phthalocyanine molecules. In the present project we plan a detailed study of selected organic molecules deposited on these rare earth modified silicon surfaces in order to determine the atomic structure and morphology of the films, the mechanisms for ordered growth, and their electronic and chemical properties. For this purpose, we employ scanning tunneling microscopy and spectroscopy, low energy electron diffraction, photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy. By selecting molecules with different structure and different characteristics of potentially reactive sites, we may vary the balance between the less local van-der-Waals interaction and the local chemical bonding in order to tune the mobility of the molecules and therewith their trend to form ordered layers.