An atomic structural model of (23×23)-R30° reconstruction proposed for 3C–SiC(1 1 1) crystallized islands on Si(1 1 1) by C60 precursor

The surface structures of 3C–SiC(1 1 1) crystallized islands formed by thermal chemical reaction between silicon substrate and adsorbed C60 molecules at high temperatures are studied using ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The STM images show a strong bias voltage dependence, transforming between (2×2), (23×23)-R30° and Y-type patterns under different bias voltages. A surface atomic structural model containing quarter coverage of vacancies and three different sites of surface silicon atoms is proposed to interpret the experimental observations. The dangling bond electronic states contributed by these different site Si atoms on the outermost surface layer and by the carbon atoms surrounding the vacancies are suggested to be responsible for the different tunneling conditions under different bias voltages in STM images.