Surface roughness and surface-induced resistivity of thin gold films deposited on preheated mica substrates under high vacuum
Abstract
In order to test the predicting power of quantum transport theories in thin metalic films, we prepared samples where the effect of other electron scattering mechanisms not included in the theoretical description (such as grain boundary scattering, that would increase the observed film resistivity) are carefully minimized. To select the conditions of evaporation that minimize the contribution of other electron scattering mechanisms, we prepared a number of gold films 50 nm thick evaporated at a speed of 3 nm/min onto freshly cleaved mica substrates held at different temperatures, annealing the films (after evaporation) for 1 hour at different temperatures. The unexpected result is that: (a) evaporating gold 99.9999basket filament under a vacuum of the order of 10**(-4) Pa, with the mica preheated to 270 C and annealing at 270 C, leads to a film resistivity at 300 K comparable to the bulk resistivity limited by electron-phonon scattering; (b) evaporating the films in a cleaner system, using an electron gun with the gold placed on an alumina crucible, under a vacuum of the order of 10**(-6) Pa, with the substrate and annealing temperature set as in (a), leads to a film resistivity which is about three times higher. In this work we present measurements of the temperature dependence of the resistivity between 4 K and 300 K on a family of 4 gold films of different thickness deposited onto mica susbtrates under conditions of evaporation that minimize the film resistivity observed at 300K, as well as measurements of the surface roughness of the films performed on a nanometric scale with a Scanning Tunneling Microscope running in air.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARS33011M