Mean free path and density of conductance electrons in platinum determined by the size effect in extremely thin films

Abstract

A new method was developed to determine the mean free path. ${l}_{\ensuremath{\infty}}$. and the conductivity, ${\ensuremath{\sigma}}_{\ensuremath{\infty}}$, of charge carriers in metals by investigating the thickness dependence of the conductivity of thin films. The method includes also surface effects as given by the specularity parameter $p$ and the surface roughness amplitude $h$. Experimental data taken during film growth could be fitted to theoretical size-effect relations only if nonzero specularity and heterogeneous film cross section caused by the surface roughness is introduced. The method allows determination of the Fermi-surface area and the electron density of the isotropic (amorphous) films. Both are smaller than expected from published bulk material data.