Carbon induced (√3 x √3)R30° reconstruction on Si(111) surface:: a theoretical study

Various atomic structural models of recently observed carbon induced (root3 x root3)R30degrees reconstruction on Si(111) surface are studied by first-principles calculations. It is found that among the four possible configurations C-T-4, C-H-3, C-S-5 and C-S-4, the most stable one is C-S-5, which consists of a substitutional carbon atom directly below the Si adatom at T-4 site. The stability of the C-S-5 configuration is attributed to the relief of the stress caused by the short Si-C bond. The electronic structures of thermodynamically stable configuration C-S-5 and the kinetically favored C-T-4 configuration are studied. The calculated electronic structures show that both C-S-5 and C-T-4 surfaces are metallic. Based on the calculated STM images at different biases and the calculated density of states, we provide a scheme to distinguish which model is observed in the experiments. (C) 2003 Elsevier B.V. All rights reserved.