III-V compounds and piezoelectric ceramic thin films deposited by reactive PLD: application to sensor building

High quality AlN, GaN, ZnO and PZT thin films were deposited on different substrates by laser ablation of metallic or PZT targets in nitrogen or oxygen reactive atmosphere. A YAG laser ((lambda) equals 1.06 micrometers , tFWHM equals 10 ns, 0.3 J/pulse) was used as laser source. The target collector distance was varied in the range 3 - 8 cm, the gas pressure in the range 10-3 - 10-1 mbar, the collectors were heated at temperatures between 200 and 400 degree(s)C. The influence of the process parameters on the physical properties of the deposited films was analyzed. The profile of atoms inside the film was evidenced by SIMS analysis. Depth profile XPS and AES confirm the presence of Al-N, Ga-N and Zn-O bonds inside the films. X-ray diffraction studies revealed different crystalline orientation depending on deposition conditions. The recorded spectra show the crystalline orientation of the layers, at collector's temperatures lower than the best results reported in literature. Optical absorption spectroscopy studies in the UV and visible range evidenced a high transparency (over 80% transmission) for the AlN, GaN and ZnO deposited films. For PZT a particular result consists in the piezoelectricity of the deposited films `as received', without any subsequent thermal or electric treatment.