Field Ion Evaporation from Tip and Sample in the STM for Atomic-Scale Surface Modification

Abstract

In a scanning tunneling microscope (STM) operated in ultrahigh vacuum, if we place a well-prepared Ag, W, Pt or Au tip above the Si(11l)-7x7 surface at a separation of ~1 nm and apply an appropriate voltage pulse to it, we can extract a single Si atom from a predetermined position routinely. The extracted Si atoms are redeposited to the surface with a certain probability. The redeposited Si atom can be displaced intentionally on the surface. In case of the Si(001)-2x1 surface, usually two Si atoms forming a dimer are extracted at the same time. For both surfaces, Si atoms at crysallographically different sites including those at step edges are extracted with different probabilities. The microscopic mechanisms of these processes are discussed.