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

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 degreesC temperatures and an increase in the substrate temperature after 80 degreesC 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 degreesC 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. (C) 2003 Elsevier Science B.V. All rights reserved.