Optical coefficients of nanometer thickness copper films in frequency range 9–11 GHz

The reflection, transmission, and absorption coefficients of ultrathin copper films on a quartz substrate in a waveguide at frequencies of 9–11 GHz were measured. Films less than 5 nm thick are almost completely oxidized and transparent to microwave radiation. A conductive layer is formed when the film thickness exceeds 5 nm, however, the reflection coefficient increases with a thickness in the range of 5–15 nm more slowly than it follows from calculations utilized the model conductivity of a continuous film. The results can be explained by the morphology of the films.