Influence of the plasma parameters on the properties of aluminum oxide thin films deposited by laser ablation

The plasma produced by the ablation of a high purity Al₂O₃ target, using the fundamental line (1064 nm) of a Nd:YAG laser, was characterized. The laser fluence was varied in order to study its effect on the characteristics of the produced plasma as well as on the properties of the material deposited. Optical emission spectroscopy (OES) was used to determine the type of excited species present in the plasma. The mean kinetic energy of the ions and the maximum plasma density were determined from the time of flight (TOF) curves, obtained with a planar Langmuir probe. The obtained results reveal that the fast peak in the probe curve could be attributed to Al III, while the slow peak corresponds to the Al II. Aluminum oxide thin films were then deposited under the same conditions of the diagnosed plasma, in an attempt to correlate the plasma parameters with the properties of the deposited material. It was found that when Al II ion energies are lower than 461.0 eV the films deposited have structural characteristics similar to that of α-Al₂O₃, whereas at ion energies greater than 461.0 eV amorphous material was obtained.