Generating of ultra precision mono crystal SiC smooth Surface by controlling of interface with substrate on MBE growth

碳化硅具有高硬度、耐热性和半导体性能，被寄予厚望，成为下一代机械材料。碳化硅可用作激光和X射线反射镜、冲压模具表面和高性能轴承等体层和薄层的机械-电-光元件。作者通过Si/C(C)异质分子束外延工艺，在超高真空条件下必须同时向硅衬底提供硅和碳的两种分子态，可获得表面粗糙度超过10μm的单晶薄碳化硅薄膜。在这些实验中，分子硅是通过辐照电子束(EB)到固体硅锭并蒸发它来提供的，而C是以纯乙炔气体的形式提供的，其中C的参与比例最高。此外，蒸发的分子Si和C都可以通过溅射其固体块体来提供；因此，有几种组合来同时提供Si和C分子。然而，没有验证哪些表面性质是由不同的组合产生的，以及哪些条件在获得所需的碳化硅方面是有效的。本研究在分子束外延(MBE)合成碳化硅的各种操作条件下，测试了一系列供气入射分子的组合，并明确了供气分子和操作条件的组合原则，以获得所需的表面性质。

Silicon carbide (SiC) is highly expected as the next generation mechanical material owing to its high hardness, thermal resistance and semiconductive property. SiC can be used as a mechanical-electrical-optical component in both bulk and thin layers, such as reflection mirrors of laser and X-ray, surfaces of stamping die and high-performance bearings, etc. The author has achieved that mono-crystal thin SiC layer of up to 0.4nm rms surface roughness over 10μm length could be attained by the Si/carbon (C) hetero-MBE process, in which both of the evaporated molecular states of Si and C must be supplied to a Si substrate simultaneously under ultra- high vacuum. In those experiments, molecular Si was supplied by irradiating Electron Beam (EB) to a solid Si ingot and evaporating it, while C was supplied as pure acetylene gas that has the highest percentage of C involvement. Also, both of the evaporated molecular Si and C can be supplied by sputtering their solid bulk; hence, there are several kinds of combinations for supplying both Si and C molecules. However, it is not verified which surface properties are generated by different combinations and which conditions are effective in attaining the desired SiC. This study tested a series of combinations of supplying incident molecules under a wide range of operating conditions in SiC synthesis by MBE and some guidelines for the combination of supplying molecules and operating conditions were made clear in order to obtain the desired surface properties.