Study of density in pulsed-laser deposited amorphous carbon films using x-ray reflectivity

Abstract

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 Ts (22–300 °C) using high-resolution x-ray reflectivity. The density values ρ for the films deposited with laser power density of 8×108 W/cm2 varied from 3.10 to 2.40 g/cm3 as the substrate temperature increased from 22 to 300 °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 Ts=200 °C.