Nanosecond action of intensive laser radiation on thin TiAlN films

The spectral dependencies ($\lambda$ = 0.35–1.0 $\mu$m) of the transmittance and reflectivity $(R)$ of TiAlN thin films deposited on glass and Si substrates by magnetron sputtering technique have been measured. The TiAlN/Si films of 0.5 $\mu$m thickness were irradiated by single nanosecond (70 ns) ruby laser pulses in order to study the influence of laser-induced thermophysical processes in TiAlN on its $R(t)$ dynamics at the wavelengths $\lambda_1$ = 0.53 and $\lambda_2$ = 1.06 $\mu$m of probing radiation, and on the state of laser irradiation zones, which was studied by optical and scanning electron microscopy. The observed in the experiment and connected with the pulsed heating dynamics changes of $R$ – increase at $\lambda_1$ and decrease at $\lambda_2$ amplifies as the irradiation energy density $W$ approaches to the threshold of laser ablation of the nitride $\sim$1 J/cm$^2$. Laser-induced thermophysical processes, occurring at $W$ = 0.6–0.9 J/cm$^2$, lead to a specific modification of the TiAlN layer with the formation of a net of cracks due to thermal stresses arising during the laser pulse. The increase of $W$ leads to the formation of a more developed net/cellular structure of the film with a smaller average size of cells.