Structure and electronic states of the Si(001)2 × 1/C surface by first-principles molecular dynamics calculations

To obtain a theoretical basis for the initial formation process of carbon layers on silicon substrates, we calculated the electronic states and the detailed geometry of a carbon monolayer on a Si(001) surface. With use of the first-principles molecular dynamics method, we determined the optimized geometry of the Si(001)2 X 1/C surface. It is found that the symmetric dimer structure is the most stable, and the C-C bond length in the dimer is much shorter than the bond length of diamond and close to that of benze. The structure formed by the dimer bond and back-bonds is rather flat, but not a planar structure. Thus, the electronic configuration at the carbon site is intermediate between sp³ and sp².