Various atomic structural models of observed carbon induced (√3 x √3)R30° reconstruction on Si(111) surface were studied by first-principles calculations. It was found that among the four possible configurations C–T4, C–H3, C–S5 and C–S4, the most stable one was C–S5, which consisted of a substitutional carbon atom directly below the Si adatom at T4 site. The stability of the C–S5 configuration was attributed to the relief of the stress caused by the short Si–C bond. The electronic structures of thermodynamically stable configuration C–S5 and the kinetically favoured C–T4 configuration were studied. The calculated electronic structures show that both C–S5 and C–T4 surfaces were metallic. Based upon calculated scanning tunnelling microscopic images for various biases, and upon the calculated density of states, a scheme was proposed for distinguishing the model observed in experiments.

Carbon Induced (√3 x √3)R30° Reconstruction on Si(111) Surface - a Theoretical Study. X.Peng, L.Ye, X.Wang: Surface Science, 2004, 548[1-3], 51-8