Characterization of DLC coatings deposited by rf magnetron sputtering

In this work diamond-like carbon (DLC) thin films have been deposited by rf magnetron sputtering in an argon gas filled chamber using graphite target under different substrate temperatures. The bonding property was characterized by micro Raman and estimated sp3/sp2 in DLC films. Raman spectra showed that sp3-bonded carbon fraction increases from 50 to 80 °C temperatures and an increase in the substrate temperature above 80 °C results in an increase in the sp2-bonded carbon atoms in DLC thin films. Mechanical properties namely, hardness and Young’s modulus were determined by CSM™ nanohardness tester. The hardness (H) and Young’s modulus (E) were found in the range of 11–22 and 110–160 GPa, respectively, at different substrate temperatures and increased with increase of substrate temperature up to 125 °C and decreased thereafter. These results indicate that substrate temperature has a strong influence on the bonding properties of the deposited films and the changes in bonding ratio (sp3/sp2) were correlated with changes in the mechanical properties.