Application of laser-induced breakdown spectroscopy to the analysis of the composition of thin films produced by pulsed laser deposition

The application of laser-induced breakdown spectroscopy (LIBS) to determine the composition of thin films produced by pulsed laser deposition (PLD) has been investigated. The targets were Fe–Ni alloys with Fe concentrations in the range 0.2–80 wt.% and the ablated material was deposited onto glass substrates. The same infrared Nd:YAG laser was used for the film deposition, carried out in vacuum, and for the analysis, performed in air at atmospheric pressure. The single-shot line intensities emitted by the laser plasma generated with the films are up to 16 times higher than those emitted by the plasma obtained with an equivalent bulk sample. A similar plasma temperature of about 7000 K has been measured with both types of samples. Those results indicate that the ablation process is much more efficient for the films than for the bulk samples. Calibration curves of the element contents in the films have been obtained, showing good correlation and low standard deviations, typically 5% RSD. The detection limit for Fe is 300 ppm. From the LIBS data, the stoichiometry and homogeneity of the film composition has been deduced.