Structures and Electrical Properties of Fullerene Thin Films on Si(111)-7×7 Surface Investigated by Noncontact Atomic Force Microscopy

We have studied the fullerene (C 60 ) multilayer thin film deposited on the Si(111)-7×7 reconstructed surface by noncontact atomic force microscopy (NC-AFM) under an ultrahigh-vacuum (UHV) condition. The double domain structure on a terrace of the crystalline island was successfully imaged. We have also simultaneously measured the contact potential difference (CPD) by the Kelvin probe method. Small CPD variations, which are not due to coupling with the topographic image, were measured at a molecular scale.