A model of substrate surface roughness effect on the electrical properties of thin films

Abstract

In situ resistance and thickness measurements during deposition of thin NiCr films onto various substrates revealed an effect of the substrate on the electrical transport parameters. On the rough surface of ceramic substrates the thickness dependence of the resistivity could be well fitted to the simple Fuchs-Sondheimer size effect model, however, both the resistivity δ o and the mean free pathλ 0 was higher than in the case of smooth glass substrates. It is shown that these deviations-appearing as a pseudo size-effect are mainly caused by the differences in the surface geometry of the substrates. Nevertheless, the material and crystal structure of the substrate have also an influence on the growth mechanism and, consequently, on the structure and electrical properties of the films. A simple model of this virtual size effect of the electrical resistivity in thin films caused by the surface roughness of the substrate is presented.