High Pressure Deposition of Epitaxial PZT Thin Films on Sr(Nb)TiO 3

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High Pressure Deposition of Epitaxial PZT Thin Films on Sr(Nb)TiO3 O. Blanco1, J. Heiras, J.M. Siqueiros, E. Martínez1 and E. Andrade2 Centro de Ciencias de la Materia Condensada, UNAM Apdo. Postal 2681, C.P. 22800, Ensenada, B.C., MÉXICO 1 Posgrado en Física de Materiales CICESE/CCMC-UNAM, [email protected] 2 Instituto de Física, UNAM, MÉXICO ABSTRACT Epitaxial thin ferroelectric films of Pb(Zr0.53Ti0.47) (PZT) were successfully grown on Sr(Nb)TiO3 (SNTO) single crystal substrates by high-pressure rf sputtering. Pure O2 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 O2 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. INTRODUCTION Lead zirconate-titanate (PZT) is the most investigated ferroelectric material because of its remarkable ferroelectric properties and its many technological applications [1]. However, several phenomena associated to the thin film preparation process, such as Pb loss during film growth and oxygen vacancy generation, influence of cristallinity and thickness on film properties, interface phenomena, epitaxy control, etc. [2-4] limit these applications. Many efforts have been dedicated to solve such problems. Scores of techniques have been tested for the deposition of PZT and other Pb-base ferroelectric materials [2, 3, 5]. The influence of the oxygen pressure on the lead concentration in the plasma and resulting film has been studied by many groups [6-8], and the epitaxial growth on crystalline substrates has also been studied [4, 5, 9]. Additionally, there are many reports on the structural and interface characteristics of high quality PZT films [5, 10, 12]. However, the development of a low-cost in

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situ technique that leads to the growth of films with excellent structural, chemical and ferroelectric properties is not completely available yet. We report the deposit of in si

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