Abstract
The ultrathin insulator growing on the Si(100) surface is a very important issue for the past decades regardless of the basic scientific field or semiconductor industry manufacture. In which, the quality of interface between the insulating film and silicon surface becomes a more important factor for affecting overall device performance by latest device size’s shrinking. Therefore, if we can construct one platform which can better combine above insulating film and below silicon surface, the device performance will promote effectively. In this thesis, we establish two very different kinds of platform layers on Si(100) surface. The first one is single ordered atomic silicon oxide layer. By exposing oxygen atomic atoms rather than traditional method of oxygen molecular reactants, single monolayer and well-ordered silicon oxide layer can be created at room temperature. The detailed reaction process about oxygen atomic reactants reacting with Si(100) surface will be discussed. Besides, the process from the crystal to amorphous silicon oxide is also revealed clearly. The data acquiring from the XPS and STM techniques also can coincide very well on the basis of our proposed model. As for the second topic, an atomic layer of stoichiometric NaCl was formed on a covalent Si(100) surface after two successive half-reactions at room temperature. The first half-reaction due to Cl2 exposure generates a square array of Cl adatoms with a distance close to that in a NaCl(100) surface plane. By utilizing scanning tunneling microscopy(STM) and core-level photoemission spectroscopy, it was found that progressive deposition of Na in the second-half reaction results in clusters, patches, and eventually turns the Cl-adlayer into a single-terrace, wavy NaCl layer at one monolayer Na coverage. The grown NaCl monolayer rolls over atomic steps like a carpet and covers the entire surface. The atomic and electronic structure of the topmost Si layer underneath the NaCl layer resembles that of the initial silicon surface layer with buckled dimers. Results of the comprehensive investigation together suggest that an ionic NaCl monolayer is very weakly bonded to the covalent substrate and appears nearly free standing.