Si2CN4(010)表面特性的第一性原理研究

应用第一性原理系统地研究了不同端面Si₂CN₄(010)模型的表面特性.通过3种可能表面模型解离能的比较,表明位于SiN层内的Si—NⅡ 键结合最强,而与碳二亚胺链状结构相连的Si—NⅠ 键结合最弱,因此易于形成以Si/NⅠ 键为端面的表面.文中还研究了弛豫前后表面的原子结构和电子特性,表面的NⅠ 原子容易形成新键,这是由于不饱和的NⅠ 原子在费米能级处有较高的态密度,电子结构不稳定,相反表面C原子状态较稳定,无明显的成键趋势. 关键词： 2CN₄')" href="#">Si₂CN₄ 表面 原子结构 电子结构

First principles study on structure and property of Si2CN4 (010) surface

The structure and property of Si₂CN₄(010) surface with different terminations were studied systemically by first principles calculation. The calculated cleavage energies of each possible surface showed that the Si—NⅡ bond located at the SiN layer was the strongest,while the Si—NⅠ bond connected with the carbodiimide was the weakest. As a result,the surface with the Si/NⅠ termination was the easiest to form. We have compared the atomic structure and electronic properties of un-optimized and optimized surface models. During the optimization of structure,the unsaturated surface atom,especially the NⅠ atoms at the surface would bond with each other to decrease the surface energies,since there are prominent density of states existing at the Fermi level of NⅠ atom. At the same time,the unsaturated C atoms do not have the tendency of bonding with each other,since their electronic state are more stable than NⅠ atom.