Thin nanocrystalline diamond/amorphous carbon (NCD/a-C) composite films were prepared by two plasma-assisted techniques: microwave plasma chemical vapor deposition (MWCVD) and hybrid pulsed laser deposition (HPLD). The HPLD system was based on a combination of PLD with an additional RF discharge applied directly to the substrate holder. In order to study the influence of the major process parameters on the chemical bonding structure of the films, we varied the basic process parameters. The Raman analysis showed peaks that can be attributed to nanocrystalline diamond and to graphitic material, suggesting the presence of two phases in the films. In case of HPLD samples, the formation of NCD was enhanced by lower working pressures and RF powers. No such influence of the deposition conditions on the bonding structure was observed for the MWCVD films. (c) 2005 Elsevier B.V. All rights reserved.