Lead deficient PST Thin Films on LSCO/SrTiO 3 by RF-Sputtering
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C11.35.1
Lead deficient PST Thin Films on LSCO/SrTiO3 by RF-Sputtering E. Martínez1, O. Blanco1, A.Fundora2 and J.M. Siqueiros3 1
CICESE, Physics of Materials Graduate Program, Km. 107 Carr. Tijuana– Ensenada, C.P. 22800, B.C. México. 2 Facultad de Física, Universidad de la Habana, San Lázaro y L, 10400, Cuba. 3 Centro de Ciencias de la Materia Condensada, UNAM, Apdo. Postal 2681, C.P. 22800, Ensenada, B.C., México. ABSTRACT We have investigated the structural, chemical and electrical properties of films with Pb0.6Sr0.4TiO3 (PST60) nominal composition grown on well texturized LSCO/SrTiO3 (STO) substrates by RFSputtering. The crystal structure and electrical properties of the PST60 films are remarkably influenced by the texture characteristics of the LSCO films. The structural and ferroelectric characteristics of PST60 thin films are determined to evaluate the potential of this heterostructure for non-volatile memory applications. Epitaxy of LSCO films was confirmed before depositing PST60 films on the above mentioned substrates through 4-Circle X-Ray Diffraction analysis (θ/2θ, ω and φ scans). The XRD analysis performed on the ferroelectric PST60 layer showed that the films are textured and entirely perovskite phase. LSCO and PST60, crystallize in the perovskite structure and their lattice parameters are well matched. This fact renders favorable structural and chemical conditions for the growth of PST60 on LSCO. The electrical performance of the Pt/PST60/LSCO/SrTiO3(001) capacitors was evaluated through Polarization-Voltage (P-V), Current-Voltage (I-V) and Fatigue measurements.
INTRODUCTION Much attention has been paid to the application of ferroelectric thin films, such as PbTiO3 (PTO), Pb(Zr,Ti)O3 (PZT) and Pb1-xLaxTiO3 (PLTO) to the fabrication of integrated capacitors for dynamic random access memory (DRAMs) due to their high dielectric constant, and for nonvolatile ferroelectric random access memory (NVFRAMs) because of their large and reversible remanent polarization characteristics [1]. La3+ doping of PTO thin films is known to increase their room temperature ferroelectric properties via the reduction of the Curie temperature of the PTO materials. However, substitution of Pb2+ ions by trivalent La3+ ions will induce the formation of Pb vacancies, which may result in the deterioration in the thin film’s ferroelectric properties, especially the fatigue behavior [2]. In recent works, the advantage of using Sr2+ ions as substitutional additive for Pb2+ ions in PTO has been pointed out, such as in the Pb1-xSrxTiO3 (PST) system, to avoid the deleterious effect caused by a trivalent substitution. In addition, ferroelectric capacitors with conductive oxide electrodes have shown superior fatigue resistance over those with metallic electrodes such as Pt [3-7]. Conductive metallic oxide La0.5Sr0.5CoO3 (LSCO) is a perovskite structure with lattice parameter matching very well with both of SrTiO3 and PST perovskite. LSCO has been extensively studied recently as an electrode material for ferroelectric thin film capacito
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