High Pressure Deposition of Epitaxial PZT Thin Films on Sr(Nb)TiO₃

Abstract

Epitaxial thin ferroelectric films of Pb(Zr 0.53 Ti 0.47 ) (PZT) were successfully grown on Sr(Nb)TiO 3 (SNTO) single crystal substrates by high-pressure rf sputtering. Pure O 2 was used as working gas at a pressure above 1 Torr. Deposition temperature was varied from 550°C to 600°C. Under these conditions we were able to deposit films at a rate of 2.7 Å/min. Their crystalline properties, evaluated by θ/2θ, ω and φ scans, showed both in-plane and out of plane orientation. Film composition and film-substrate interface characteristics were studied by Rutherford Backscattering Spectroscopy (RBS). For RBS data the composition ratios for the films were calculated having obtained the expected values for a stoichiometric composition. A very thin diffusion layer of Pb at the film-substrate interface was also introduced. However, the deficiency in Pb, which is correlated to the presence of oxygen vacancies, is lower in our films produced at high O 2 pressure than those reported for films produced by sputtering at lower pressures. The ferroelectric hysteresis loops measured in the Pt/PZT/SNTO heterostructures show good ferroelectric behavior with remanent polarizations of 12µCcm -2 and coercive field of 50kVcm -1 at 5V. The high-pressured technique representing a useful and capable method capable of obtaining in situ epitaxial, fully oxygenated, pyrochlore-free ferroelectric thin film with high quality structural, compositional and dielectric properties, without post deposit treatment.

Strain and Grain Size Effects on Epitaxial PZT Thin Films

“…The characterization of ferroelectric properties made by the hysteresis loops measurements en film deposited on Sr(Nb)TiO 3 substrates, had been reported elsewhere [5,6]. Figure 8 shows a typical hysteresis loops obtained in this structure.…”

“…Epitaxial ferroelectric thin films of lead zirconium-titanium oxide, Pb(Zr 0.53 Ti 0.47 )O 3 (PZT), were RF sputtered onto SrTiO 3 (STO), LaAlO 3 (LAO), and Sr(Nb)TiO 3 (SNTO) single crystal substrates by a modified RF sputtering technique at high oxygen pressures as reported previously [5,6]. The relevant deposition conditions are summarized in the Table I.…”