Nanostructures on oxidized Si surfaces fabricated with the scanning tunneling microscope tip under electron-beam irradiation

Abstract

Atom transfer from an oxidized Si surface to the tip of a scanning tunneling microscope (STM) was achieved for samples at room temperature, when the tip-sample interaction area is irradiated with an external electron beam. The transfer proceeded stably with use of a Si apex of the STM tip and of a thin Ge coverage on the oxidized Si surface. The extraction of atoms from the sample occurred at negative tip bias voltages, producing nanosized Si windows in the Si oxide film. Atoms accumulated on the tip apex during the extraction can be redeposited back to the windows at positive tip bias voltages. The mechanism of extraction is related to chemically assisted field evaporation, which was realized due to relatively strong bonding strength of extracted atoms to the surface of the Si tip apex.