Measuring the Microwave Conductivity of Platinum Ultrathin Films

The measurements of the reflection and transmission coefficients of platinum films with thicknesses of 1-30 nm fabricated on quartz substrates using magnetron sputtering are reported. The measurements were conducted in a rectangular waveguide at frequencies of 9-11 GHz. For a wave falling onto the Pt film from the quartz substrate side (Q-Pt orientation), the growth of the absorption coefficient (A(max) = 0.45) and the presence of a pronounced minimum of the reflection coefficient (R-min = 0.23) for the 3-nm-thick film have been observed. In films thinner than 10 nm, the values measured are consistent with the calculations performed with the model thickness dependence of conductivity. The specific conductivity of the Pt films as a function of thickness has been calculated using the approximate boundary conditions and the measured reflection coefficients.