Irradiation of the amorphous carbon films by picosecond laser pulses

• The picosecond laser irradiation led to the rearrangement of sp3 C-C to the sp2 C = C bonds in the diamond-like carbon film.
• The ps-laser irradiation of the DLC films stipulates appearance of the aromatic carbon structures.
• The bonding type of the graphite-like carbon films remained unchanged even after ps laser irradiation with 100 pulses.

The effect of a picosecond laser irradiation on structure modification of diamond-like carbon (DLC) and graphite-like carbon (GLC) films was analyzed in this work. The DLC films were irradiated by Nd:YVO4 laser operating at the 532 nm wavelength with the picosecond (10 ps) pulse duration at the fluence in the range of (0.08–0.76) J/cm2. The GLC films were irradiated only at the fluence of 0.76 J/cm2. The different pulse number (1, 10, and 100) was used for irradiation the films. The micro-Raman spectroscopy measurements indicated that the laser irradiation led to rearrangement of the sp3 C–C bonds to the sp2 CC bonds in the DLC films. The formation of silicon carbide (SiC) was found in the irradiated spot after 10 and 100 pulses. Modifications in the structure of the DLC film took place even in the areas with low intensity of the Gaussian beam wings (heat affected areas). The increase in the oxygen concentration up to ten times was detected in the heat affected areas after 100 pulses. Opposite to that, the laser irradiation decreased the oxygen concentration and smoothened the surface microrelief of the GLC films. The bonding type remained unchanged in the GLC films even after irradiation with 100 pulses per spot.