Visible Raman spectroscopy of carbon films synthesized by ion-plasma sputtering of graphite

The article discusses the structure and properties of noncrystalline carbon films synthesized by ion-plasma sputtering of a graphite target in an argon atmosphere at direct current. Analysis of the molecular structure of carbon films was performed using Raman spectroscopy and dependence of the structure of synthesized films on the synthesis temperature and substrate material was revealed. Besides the main G peak possesses the values in a broad frequency range from 1500 to 1575 cm−1. The evolution of molecular structure peculiarities of synthesized carbon films depending on the synthesis conditions was clearly shown using the numerical methods of the Raman spectra decomposition. Studies of the optical spectra showed that the band gap of synthesized films varies from 0.78 to 1.67 eV and with increasing optical band gap, the value of G peak position decreases under laser excitation of 2.62 and 1.96 eV.