CHARACTERIZATION OF PB0.97ND0.02(ZR0.55TI0.45)O3 THIN-FILMS PREPARED BY PULSED-LASER ABLATION

Pulsed laser ablation was used to deposit Nd-doped lead zirconate tita nate (PZT) thin films with thickness 100-200 nm from a Pb0.97Nd0.02(Zr 0.55Ti0.45)O3 target. The films were ablated onto sapphire substrates with R -plane surfaces, without heating and at a pressure of 5 x 10(-5 ) mbar using a XeCl excimer laser (pulse energy about 50 mJ, wavelengt h 308 nm, pulse duration about 20 ns). Energy dispersive spectroscopy (EDS) of x rays was used for the composition analysis of both annealed and unannealed (amorphous) films deposited using various substrate-ta rget distances and laser-beam fluences. It was found that the distance between target and substrate together with the laser-beam energy dens ity on the surface of the target had a significant effect on the compo sition of the films. From the composition analysis, a suitable range o f values was found for the target-substrate distance and fluence to de posit films with correct composition of each component. Lead deficienc y was also found in the films in the case of high fluence (>1.5 J cm-2 with the target-substrate distance <40 mm), probably due to resputter ing, while low fluence values (<1.0 J cm-2 with the target-substrate d istance >40 mm) gave an excess of lead and too high Ti/(Zr+Ti) ratios. The films were annealed 2 h at 750-degrees-C with and without PZT pow der. The composition analysis revealed that the films with an excess o f lead before annealing had almost the correct amount of lead after an nealing. On the other hand, it was not possible to compensate the lead deficiency through annealing in a lead atmosphere. EDS and x-ray diff raction were used to determine the crystal structure of annealed films . Trigonal and tetragonal perovskite structures were the major and min or phases of the films, respectively. Some Raman spectra measured from annealed films were found to be typical to PZT.