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 synthe size carbon nitride coatings having a general formula CNx. In previous expe riments, 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 f ew hundreds of nanometers of size. This phenomenon was tentatively explaine d by the abundance of vapors generated by the action of the laser. It can b e, in turn, related to the thermal fields in the graphite target. The numer ical code 'Fusion-2D', describing laser/target interaction, was applied to model the temperature in two dimensions. The optical absorption data were t aken for the wavelengths that corresponded to the typical lasers used in PL D processes, i.e. excimer, YAG and CO2. The evolutions in the graphite targ et temperature at the pulses generated by these lasers were then calculated for a given power density. The differences in these evolutions were relate d 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.