Effects of argon ion bombardment on the microstructures and electrical conductivities of hydrogenated amorphous carbon films prepared by plasma-enhanced chemical vapor deposition

Hydrogenated amorphous carbon films were prepared from plasma-enhanced chemical vapor deposition. Films thermally annealed at 300 °C for 2 h as well as those as-deposited films exhibited insulating characteristics. The as-deposited films were found to possess mainly polymerlike structures. A hydrogen etching effect was observed in these films after argon-plasma bombardment. The implanted argon ions transferred momentum to atoms in films which led to both a reduction in the polymer content and also an increase in the graphite and diamond contents in both as-deposited and annealed hydrogenated amorphous carbon films. This change in the microstructures resulted in an increase in the electrical conductivity up to six orders of magnitude at room temperature. In addition, films which exhibited thermally activated conductivity characteristics were found and an activation energy of around 0.3 eV was measured.