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

碳化硅（SiC）具有高硬度、高耐热性、高耐磨性等优点，被认为是下一代机械材料。SiC可用作体材料和薄层材料的机电光元件，如激光和X射线反射镜、冲压模具表面和高性能轴承等。作者采用Si/C异质分子束外延技术，获得了10μm以上、均方根粗糙度达0.4nm的单晶SiC薄层，其中Si和C的蒸发分子态必须在超高真空下同时提供给Si衬底。在这些实验中，通过将电子束（EB）照射到固体Si锭并使其蒸发来提供分子Si，而C作为具有最高百分比的C参与的纯乙炔气体来提供。此外，蒸发的分子Si和C都可以通过溅射它们的固体块体来供应;因此，存在用于供应Si和C分子的几种组合。然而，还没有验证哪些表面性质是由不同的组合产生的，以及哪些条件对获得所需的SiC是有效的。本研究测试了分子束外延合成SiC过程中在各种操作条件下的一系列供给入射分子的组合，并明确了供给分子和操作条件的一些组合准则，以获得所需的表面性能。

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.