Influence of Deposition Parameters and Substrate on the Quality of Pulsed-Laser-Deposited Pb1-xCaxTiO3 Ferroelectric Films

Pb_{1- x} Ca _x TiO₃ (PCaT) thin films have been prepared by pulsed laser deposition (PLD) on Pt/TiO₂/SiO₂/(100)Si, (100)MgO, and Pt/(100)MgO substrates. 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 temperature for the Pb loss changes from 250°C using nonsintered targets to 450°C if sintered targets are used; moreover, the sintered targets also produce a low particle density on the film surface (0.4 µm^?2). Increasing the laser fluence to about 10 J/cm² improves the crystalline quality of the films. PCaT ( x = 0.24) films obtained by PLD on Si-based substrates have a lattice tetragonality c / a = 1.014, lower than the value obtained in films prepared by other methods. The film tetragonality can be slightly increased to c / a = 1.022 by using MgO substrates and much more efficiently by reducing the Ca concentration, up to reach c / a = 1.048 in Ca free films. The increase of the film tetragonality induces an enhancement of the film orientation with the 001] axis perpendicular to the substrate surface; moreover, the typical values of the spontaneous and remanent polarizations increase up to P _r similar/congruent 34 µCcm^?2.