Fabrication of gold nanostructures on a vicinal Si(111) 7×7 surface using ultrahigh vacuum scanning tunneling microscope and a gold-coated tungsten tip

We have demonstrated that nanometer-scale gold dots can be deposited on a vicinal Si(111) 7×7 surface using the field-assisted atom transfer from the gold-coated tungsten tip of a scanning tunneling microscope operating in ultrahigh vacuum. With the application of negative voltage pulses to the tip, gold nano-mounds with the size ranging from ∼3 to ∼20 nm across at the base and 0.6–1 nm high can be created on the surface. The deposition is found to be more favored on the step edges than the (111) terraces. Since atomically resolved images of the Si(111) 7×7 structure can be observed even after many cycles of atom transfer using the gold-coated tip, the shape of the tip apex has been kept very stable. The overall findings clearly suggest that the atom-transfer technique proposed here is proven to be a good candidate for fabricating nanometer-scale devices.