Structure and properties of diamondlike carbon films produced by pulsed laser deposition

Pulsed laser deposition was used to produce hydrogen-free amorphous diamondlike carbon (a-C) and hydrogenated amorphous diamondlike carbon (a-C:H) from graphite and polycarbonate targets, respectively. Films were grown under identical conditions in high vacuum at low temperatures onto steel and Si substrates. The a-C films were uniform, while a-C:H films contained a great number of particles ejected from the target surface. The a-C films have hydrogen contamination about 0.1 at. %, while a-C:H have about 25 at. % H and 10 at. % O. High percentages of sp(3) bonding were found in both films. Film densities were estimated to be 3.0 g cm(-3) for a-C films and 2.2 g cm(-3) for a-C:H films. Chemical and structural characteristics of the films were correlated with their thermal stability and mechanical properties. Temperatures for starting graphitization were about 500 degrees C for a-C and 350 degrees C for a-C:H. The presence of hydrogen reduced film hardness from 60 GPa for a-C films to 14 GPa for a-C:H films. Hydrogen was also associated with dependence of a-C:H films friction coefficient on environment and with higher wear rates of a-C:H films in comparison to a-C films. (C) 1996 American Vacuum Society.