Modification of amorphous DLC films induced by MeV photon irradiation

Modification of the properties of amorphous diamond-like carbon (DLC) coatings irradiated by MeV photons from medical linear accelerator has been investigated. DLC structures of different content and thickness, synthesized under different technological parameters at room temperature using direct ion deposition (cold cathode) method were used for the investigation. Properties of the irradiated carbon films were studied using UV/VIS spectrometry and laser ellipsometry. Bonding structure of the samples was analyzed by Fourier transform infrared (FTIR) spectrometry and Raman scattering (RS) spectroscopy. Investigated DLC films indicated increased optical transparency which was different for the films with different networking structure. No significant structural changes were found in irradiated SiOx-containing and additionally N2 co-doped DLC films. Reduction of permittivity was observed in all irradiated samples.The results of investigation are analyzed in accordance with the registered radiation induced changes in investigated samples and possible model of the X-ray photon interaction with amorphous DLC films is discussed.