Impact of microstructure on the optical properties of ruthenium thin films

Optical properties of multiple types of Ru thin films spanning the range from UV to IR are reported for the first time. We show that the refractive index of these monatomic metallic thin films is strongly affected by the film's crystallographic attributes. Specifically, conductivity in the infrared is observed to correlate strongly with the grain structure of the film. Thin film microstructure should therefore be considered in regard to the applicability of the referenced optical constants of metals. Accordingly, we present optical constants for a set of four Ru films, each having a different grain structure.