Electric Field Heating of Supported and Free-Standing AuPd Fine Wires
Using electron-beam lithography, fine AuPd wires of 50 nm and 30 nm thickness have been fabricated over a length of 10 μm on a Si3N4 substrate. The resistance rise as a function of temperature fits well to one-dimensional Coulomb interactions for low temperatures. On etching away the substrate the functional form of the resistance rise changes and cannot be fitted to theory. It is found that for a supported wire the energy loss is limited by the electron-phonon scattering rate which is proportional to the square of the electron temperature. For a free-standing wire the heat loss is limited by diffusion of electrons and phonons along the wire. Recently 100 nm width and 5 nm thickness have been made free standing over a length of 15 μm.