INFLUENCE OF DEPOSITION PARAMETERS AND SUBSTRATE ON THE QUALITY OF PULSED-LASER-DEPOSITED PB1-XCAXTIO3 FERROELECTRIC-FILMS

Pb1-xCaxTiO3 (PCaT) thin films have been prepared by pulsed laser depo sition (PLD) on Pt/TiO2/SiO2/(100)Si, (100)MgO, and Pt/(100)MgO substr ates. A Pb deficiency with regard to the target composition occurs in films prepared on heated substrates, while the Ca concentration in the film remains congruent with the target composition. The onset tempera ture for the Pb loss changes from 250 degrees C using nonsintered targ ets to 450 degrees C if sintered targets are used; moreover, the sinte red targets also produce a low particle density on the film surface (0 .4 mu m(-2)). Increasing the laser fluence to about 10 J/cm(2) improve s the crystalline quality of the films. PCaT (x = 0.24) films obtained by PLD on Si-based substrates have a lattice tetragonality c/a = 1.01 4, lower than the value obtained in films prepared by other methods. T he film tetragonality can be slightly increased to c/a = 1.022 by usin g MgO substrates and much more efficiently by reducing the Ca concentr ation, up to reach c/a = 1.048 in Ca free films. The increase of the f ilm tetragonality induces an enhancement of the film orientation with the [001] axis perpendicular to the substrate surface; moreover, the t ypical values of the spontaneous and remanent polarizations increase u p to P-r approximate to 34 mu C.cm(-2).