Mechanical distinction and manipulation of atoms based on noncontact atomic force microscopy

Using noncontact atomic force microscopy (NC-AFM), we have succeeded in imaging two-dimensional (2D) Ge islands as well as Ge atom clusters on Si(1 1 1)-(7 × 7) surface with atomic resolution. We have investigated the tip-sample distance dependence of NC-AFM images of oxygen adsorbed Si(1 1 1)-(7 × 7) surface, and achieved the chemical distinction between oxygen and Si atom species. Besides, using a soft nanoindentation based on the NC-AFM method for mechanically manipulating Si adatoms of the Si(1 1 1)-(7 × 7) surface, we have achieved atom removal, i.e., vertical manipulation, at tip and sample temperature of 78 K as well as at room temperature (RT). In addition, as an application of this soft nanoindentation method, we have produced the lateral displacement of Si adatoms towards metastable positions in the half unit cell of the Si(1 1 1)-(7 × 7) reconstruction at 78 K.