Atom manipulation and image artifact on Si(1 1 1)7×7 surface using a low temperature noncontact atomic force microscope

We investigate the capability of single atom manipulation using the noncontact AFM operating low temperatures. Here, for the first step of atom manipulation, we try to perform the vertical manipulation. By applying the bias voltage between Si(1 1 1)7×7 surface and the tip of the conductive AFM cantilever, we succeed in removing the adatoms from the surface for the first time. This experimental result opens a new research field with the noncontact AFM. Furthermore, by analyzing the noncontact AFM images measured on Si(1 1 1)7×7 surfaces, we propose a model for the atomic arrangement of the Si tip apex with an asymmetric ad-dimer.