Effect of ambient gaseous environment on the properties of amorphous carbon thin films

Amorphous carbon films have been deposited by filtered cathodic jet carbon arc technique under different gaseous environments. Scanning electron microscope and atomic force microscope studies have been performed on the deposited films for the surface morphological studies. The morphology of the deposited film changes with the change in gas environment. X-ray photoelectron spectroscopic (XPS) and Raman studies have been carried out on the deposited samples for the evaluation of the chemical bonding of carbon atoms with the ambient gas atoms. The sp3 and sp2 contents have been evaluated from the XPS studies and found to be dependent on the gaseous environment. The film deposited under hydrogen environment has the highest value of the sp3 content (54.6 at.%) whereas the film deposited under helium environment has the lowest value of sp3 content (37 at.%). For the evaluation of the electrical and mechanical properties of the deposited films, the electrical conductivity and nanoindentation measurements have been performed on the deposited films. It has been observed that the film deposited under helium environment has the highest electrical conductivity and the lowest hardness (∼15 GPa) value whereas film deposited under hydrogen environment has the highest hardness (∼21 GPa) and the lowest conductivity.