Contamination of Amorphous Carbon Thin Films: Modelling the Transport of Atoms in Gases During Deposition

Monte Carlo simulations of the transport of atoms in gases related to the deposition process and the contamination of amorphous carbon thin films during deposition in magnetron discharges have been performed. These films are of interest in accelerator technology due to their low secondary electron yield when their structures are dominated by sp2 carbon. Two codes, which practically share the same algorithm, are introduced: TAGs 1 simulates the transport of sputtered atoms from the target to the substrate, and TAGs 2 simulates the transport of atoms from the plasma towards the target and the substrate. The similar results of TAGs 1 and the well-established SIMTRA for the same input parameters imply the algorithm’s accuracy. The codes were used to model the transport of different atoms (C, H, O, D) in a magnetron Ar discharge. The simulations reveal that the operating pressure should be higher than 1 Pa for a sample-target distance of 90 mm to secure sp2 carbon formation. The contamination mechanisms of amorphous carbon coatings were then studied by merging the results obtained with both programs. Preliminary comparisons with experiments suggest that the combined results of TAGs 1 and 2 agree very well with the experiments.