Theoretical modelling of phenomena in the pulsed-laser deposition process: Application to Ti targets ablation in low-pressure N2

We present an analysis describing the phenomena that are involved in the interaction process between high intensity UV laser radiation and a solid target in a low-pressure gas environment. The laser action upon the solid surface is described by solving the one-dimensional (1D) heat-conduction equation. The 1D hydrodynamic model is further applied to describe the interaction between laser radiation and the plasma expanding in front of the target. The laser radiation absorption in the vapor plasma is considered using a multicomponent fluid model. The transit of ablated material from target to collector is treated by a Monte Carlo method. The time and space distributions of the main plasma parameters (e.g., atom density and plasma electron temperature and density) are calculated. Finally, the thickness profile of a film deposited on a collector parallel to the target is predicted. For comparison with available experimental data, the calculations were carried out for the case of a Ti target submitted to a multipulse UV laser irradiation in low-pressure nitrogen, when depending on gas pressure, stoichiometric TiN was deposited or mixtures of amorphous and crystalline Ti, TiN, Ti2N, and even Ti oxides were obtained.