| In recent years, low-dimensional materials have attracted extensive attention due to their potential applications in electronic industry. While first principle method based on density function theory (DFT) can play an important role in revealing the basic properties of this kind of low-dimensional materials and devices. In this thesis, we paid our attention to the first principle calculation method as well as its latest development; furthermore, we focus on applying this method in studying the most popular materials in this area.Surface is the most active region in solids, for it is where the reactions between solid and environment take place. Both chemical catalysis and electronic industry are constructed on the surface science. More importantly, surface is a two-dimensional structure and the end of periodical structure of solid, and has many unique properties. Therefore, the structure and properties of various semiconductor surfaces are always the emphases in condensed matter physics research. We here focus our work on the structure and electronic properties of Silicon Carbide surface.We perform first-principles calculations to explore the physical origin of hydrogen-induced semiconductor surface metallization observed in 3C-SiC(001)-3×2 surface. We show that the surface metallization arises from a novel mechanism of n-type doping of surface band via formation of Si-H-Si hydrogen bridge (HB) bonds. The hydrogen strengthens the weak Si-Si dimers in the subsurface by forming HB bonds, and donates one electron (per hydrogen) to the surface conduction band. We calculate the vibration frequency of H in the Si-H-Si bond, which agrees well with the experiment. This confirms the physical mechanism proposed by us.
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