Optical properties of organic material produced in a dusty plasma

Thin films of organic material produced in a dusty plasma in N2–CH4 mixtures are deposited on silicon substrates. The real (n) and imaginary (k) parts of the complex refractive index are determined using the spectroscopic ellipsometry technique in the 370-1000 nm wavelength range. The optical index depend strongly on the methane concentrations: k values decreases with initial CH4 concentration, while the real optical index (n) increases. Thanks to Mid-infrared spectra recorded for thin films, the larger absorption in the visible range is explained by an increase of the secondary and primary amines signatures.