Modification of characteristics of diamond-like carbon thin films by low chromium content addition

Diamond-like carbon thin films with low chromium content have been deposited by Electron Cyclotron Resonance Chemical Vapor Deposition (ECR-CVD) using a metallic target as chromium source. Major changes in the characteristics of the coatings have been shown as a result of the incorporation of Cr into the film. Raman spectroscopy reveals that the chromium incorporation leads to a reduction in the structural disorder, associated with a higher percentage of six-fold rings. An enhancement in film durability due to metal addition has been detected by pin-on-disk tests. Moreover, as measured by Atomic Force Microscopy (AFM), chromium doping of the diamond-like carbon film produces an increase in the electrical conductivity. The I–V characteristics, as obtained from Current Imaging Tunneling Spectroscopy (CITS) heating tests, in the 25–200 °C range suggest that metal contribute to the electrical conductivity by tunneling between the metal clusters and by enhancing the formation of conductive graphite-like structures, which also participate actively in the conduction process.

► In situ method for Cr addition (low content) into DLC films by ECR-CVD.
► Improvement in the durability in Cr-DLC films by low metal addition.
► Electrical conductivity enhancement by metal and sp2 carbon clusters contribution.