STUDY OF DENSITY IN PULSED-LASER DEPOSITED AMORPHOUS-CARBON FILMS USING X-RAY REFLECTIVITY

We report the accurate determination of the absolute density of the pulsed-laser deposited amorphous carbon ultrathin films as well as the film density evolution with the substrate temperatures T(s) (22-300-degrees-C) using high-resolution x-ray reflectivity. The density values rho for the films deposited with laser power density of 8 X 10(8) W/cm2 varied from 3.10 to 2.40 g/cm3 as the substrate temperature increased from 22 to 300-degrees-C. This result, together with the optical band-gap values obtained by transmittance measurements, clearly indicates a diamond-like to graphite-like microstructure change near T(s) = 200-degrees-C.