Effects of substrate temperature on bonding structure and mechanical properties of amorphous carbon films

Abstract

Diamond-like carbon thin films were prepared at different substrate temperatures by RF magnetron sputtering of a graphite target. The chemical bonding of the carbon structure was characterised by Raman spectroscopy. Raman measurements showed that sp 3 bonded carbon fraction increases from 50 to 80 °C temperatures and an increase in the substrate temperature after 80 °C results in an increase in the sp 2-bonded carbon atoms in DLC thin films. Mechanical properties, namely hardness and Young's modulus were determined by CSM TM 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 (sp 3/sp 2) were correlated with changes in the mechanical properties.