Conductance of tip–surface and tip–atom junctions on Au(111) explored by a scanning tunnelling microscope

Abstract

The conductance between the tip of a scanning tunnelling microscope and a Au(111) surface is measured at tip–surface distances comprising tunnelling and contact regions. Contact between the tip and the flat sample surface as well as between the tip and an individual gold atom can be performed reproducibly without deteriorating the imaging capability of the instrument. Measurements performed on the face-centred cubic and hexagonal close-packed stacking domains of the Au(111) surface reconstruction lead to similar conductances of one quantum of conductance at contact.