Fig. 4: Optical Properties of the UTMFs.
From: Ultrathin 2 nm gold as impedance-matched absorber for infrared light
a Measured transmittance and reflectivity of (seeded) Au layers, obtained by FTIR spectroscopy. All spectra are fitted by the given Drude Model Eq. (1), including the measured resistivity. R2 is the coefficient of determination for each fit. As for thicker layers, all spectra are in good agreement with the optical properties of a metallic film, the layers below 2 nm show a divergence, due to the insulator-to-metal transition. For the metallic-like layers, the obtained plasma frequency remains constant with ωp ~ 2π·3.0(7) PHz. b Absorptivity as a function of deposited gold thickness and wavelength obtained experimentally from FTIR measurements. The data has been linearly interpolated for the plot. Each horizontal grid line corresponds to a sample. All measured layers were evaporated on 50 nm SixNy membranes comprising an oxidized copper seed layer. c Calculated absorptivity using the fitted Drude parameters and measured resistivity via Eq. (1) and extracted optical properties of SixNy. Source data are provided as a Source Data file.
