The electrical resistivity of gold films

Abstract

We present measurements of the d.c. electrical resistance of three classes of pure epitaxial gold films in the thickness range 30 to 900 nm. The combination of diverse morphological techniques with temperature-dependent data from 2 to 300 K enables us to apply a new theory based on those of Mayadas and Shatzkes for grain-boundary scattering, and of Soffer for surface scattering. Gold, evaporated and annealed on mica substrates, produced (111) films which gave a mean microscopic surface roughness to Fermi wavelength ratio, r, of 0.05 and a grain-boundary reflexion coefficient, Rg, of 0.45. On KBr substrates, samples, prepared similarly, formed two distinct types of (100) film. Use of reflexion high energy electron diffraction and electron microscopy showed that the grain structure of these types of film differed; however, both gave an r of 0.1. An R _g of 0.10 was determined for one type but remained unknown for the other. Our results show how previous workers, often relying on the validity of Fuchs’s theory and the misapplication thereof, have failed to present convincing evidence for specular surface scattering. We demonstrate the necessity for, experimentally, morphological observations and measurements over a wide temperature range, and, theoretically, the use of a method that combines the effects of both grain-boundary and angular-dependent surface scattering.