Optical properties of amorphous carbon thin films deposited by thermal CVD using camphor oil

Amorphous carbon (a-C) thin films were deposited on glass at by thermal chemical vapor deposition (CVD) technique using camphor oil as the precursor. All samples were grown in fixed conditions except the deposition temperature parameter was varied. The a-C thin films were characterized by using UV-Vis-NIR spectroscopy, Scanning Electron Microscopy, Fourier Transform Infrared spectroscopy. The UV-Vis-NIR analysis was used to obtain the optical absorption coefficient. The optical band gap was decreased from 1.1eV to 0.23eV with increasing the deposition temperature. Fourier Transform Infrared (FTIR) spectroscopy was used to obtain the concentration of sp² bonded carbon in the films. The sp² and sp³ bonded carbon amount in a-C structure could effect the optical band gap of the as grown a-C thin films. These a-C thin films were found to be dependent on the deposition temperature and amount of sp³ and sp² bonded carbon.