Atom-resolved imaging of the potential distribution at Si (111) 7 x 7 surfaces

Si (111) 7 x 7 surfaces were observed at an atomic scale by noncontact atomic force microscope (neAFM) and scanning Kelvin probe microscopy (SKPM). A vacancy at the Si Surface was resolved by both ncAFM and SUM, This indicates that SKPM, as well as ncAFM, has a true atomic-scale lateral resolution. In the atom-resolved SKPM observations, two types of contrast were acquired even when the observation conditions were the same except for the surface condition of a cantilever tip. The result experimentally revealed that the contrast of all atom-resolved SKPM image strongly depended on the surface condition of the probe tip.