Reproducible fabrication of metallic silver nanostructures on a Si(111)-(7×7) surface by tip–material transfer of a scanning tunneling microscope

A technique for reproducible fabrication of nanometer-scale silver dots, wires, characters, and figures on a Si(111) surface in ultrahigh vacuum using scanning tunneling microscopy and their electronic properties are presented. This method allows patterns to be formed at will by the computer-controlled application of voltage pulses between a silver-coated tip and the surface. Scanning tunneling spectroscopy shows unambiguous metallic behavior on the nanodots and depletion layer formation in the neighboring region. The dominant mechanism of nanodot formation can be attributed to the spontaneous formation of a point contact due to field-enhanced diffusion of silver atoms to the tip apex.