C60 adsorption onto the one-atomic-layer In films on Si(111) surface

We have studied C-60 adsorption onto the In-induced Si(111) reconstructions, Si(111)2x2-In. Si(111)-hex-root 7 x root 3-In, and Si(111)-rec-root 7 x root 3-In, which all represent essentially one-atomic-layer In films residing atop a bulk-like Si(111) substrate. The reconstructions have various In densities, incorporating 0.75, 1.0, and 1.2 ML of In, respectively. We have found that C-60 adsorption onto these reconstruction is accompanied by the mass transport within In atomic layer, which is manifested by developing the domains of a more dense In/Si(111) reconstruction on the surface in between C-60. This observation provides a direct evidence for the displacement of In atoms from beneath C-60 to the surrounding surface area. The plausible driven force of the C-60-induced In displacement is a tendency of C-60 to change relatively modest bonding with In layer to a more stronger bond with Si(111) substrate. (C) 2011 Elsevier B.V. All rights reserved.