Modeling of temperature fields in the graphite target at pulsed laser deposition of CNx films

The pulsed laser deposition (PLD) technique is frequently applied to synthesize carbon nitride coatings having a general formula CNx. In previous experiments, the polycrystalline CNx films were deposited with the use of a CO2 TEA laser in a remote nitrogen atmosphere [1]. The x value was found to be approximately 0.6 and the grains, observed with SEM, were typically of a few hundreds of nanometers of size. This phenomenon was tentatively explained by the abundance of vapors generated by the action of the laser. It can be, in turn, related to the thermal fields in the graphite target. The numerical code 'Fusion-2D', describing laser/target interaction, was applied to model the temperature in two dimensions. The optical absorption data were taken for the wavelengths that corresponded to the typical lasers used in PLD processes, i.e. excimer, YAG and CO2. The evolutions in the graphite target temperature at the pulses generated by these lasers were then calculated for a given power density. The differences in these evolutions were related to the volume of produced vapors and helped to explain the morphology of the synthesized films. (C) 2001 Elsevier Science B.V. All rights reserved.