Effect of silver doping on optical property of diamond like carbon films

Optical properties of silver doped diamond like carbon films (Ag:DLC) deposited by the RF reactive sputtering technique were studied in detail. The chemical binding energy and the composition of the films were investigated by using an X-ray photoelectron spectroscopy. Optical transparency and optical band gap decreased with the silver incorporation to the DLC film. Optical band gap calculated from transmittance spectra decreased from 2.55 to 1.95 eV with a variation of Ag concentration from 0 to 12.5 at.%. Urbach parameter determined from the band tail of the transmittance spectra showed to increase with the doping concentration.