Fabrication of noble-metal nanoconstrictions and observation of conductance fluctuations

We describe the fabrication of planar metallic nanostructures with lateral dimensions down to about 80 nm and thicknesses varying from 15 to 50 nm. We use a lift‐off process with a polymethylmethacerylate bilayer resist on silicon substrate and an electron beam writer system for microfabrication. The noble‐metal layers are deposited by thermal evaporation. The geometries are point contacts, rings, and wires in two‐lead configuration. We discuss measurements of the magnetoconductance at very low temperatures and in magnetic fields up to 4 T in dependence of the width of the samples. Here the electron transport is in the diffusive regime and the width dependence of the universal conductance fluctuations is investigated.