Surface roughness and surface-induced resistivity of gold films on mica: influence of roughness modelling

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Abstract
We report measurements of the temperature dependent resistivity (T ) of a gold film 70 nm thick deposited on mica preheated to 300 °C in UHV, performed between 4 K and 300 K, and measurements of the surface topography of the same film performed with a scanning tunnelling microscope (STM). From the roughness measured with the STM we determine the parameters (r.m.s. amplitude) and (lateral correlation length) corresponding to a Gaussian and to an exponential representation of the average autocorrelation function (ACF). We use the parameters and determined via STM measurements to calculate the quantum reflectivity R , and the temperature dependence of both the bulk resistivity 0 (T ) and of the increase in resistivity (T ) = (T ) - 0 (T ) induced by electron-surface scattering on this film, according to a modified version of the theory of Sheng, Xing and Wang recently proposed (Munoz et al 1999 J. Phys.: Condens. Matter 11 L299). The resistivity 0 in the absence of surface scattering predicted for a Gaussian representation of the ACF is systematically smaller than that predicted for an exponential representation of the ACF at all temperatures. The increase in resistivity induced by electron-surface scattering predicted for a Gaussian representation of the average ACF data is about 25% larger than the increase in resistivity predicted for an exponential representation of the ACF data.