Thin Solid Films 441 (2003) 115–120 0040-6090/03/$ - see front matter  2003 Elsevier B.V. All rights reserved. doi:10.1016/S0040-6090(03)00909-X Antiferroelectric characteristics and low frequency dielectric dispersion of Pb La (Zr Ti )O thin films 1.075 0.025 0.95 0.05 3 Ill Won Kim*, Dae Su Lee, Sun Hee Kang, Chang Won Ahn Department of Physics, University of Ulsan, P.O. Box 18, Ulsan 680-749, South Korea Received 15 April 2003; received in revised form 20 May 2003; accepted 9 June 2003 Abstract La-modified lead zirconate titanate Pb La (Zr Ti )O , antiferroelectric thin films are fabricated by excimer laser 1.075 0.025 0.95 0.05 3 ablation technique on PtyTiySiO ySi substrates. The measured dielectric constant and dissipation factor are 642 and 0.021 at 2 room temperature, respectively, and Curie temperature is 196 8C. The antiferroelectric double hysteresis loops of Pb La (Zr Ti )O film are confirmed by measuring the polarization vs. the electric field. With increasing temperature, 1.075 0.025 0.95 0.05 3 the double hysteresis loop behavior is reduced and gradually becomes a loose single ferroelectric hysteresis loop. The complex dielectric constants and a.c. conductivities are measured as a function of frequency (10 –10 Hz) and temperature (25–250 8C) y2 6 in order to investigate the influence of microstructure on the charge transport mechanism. We observe the strong low-frequency dielectric dispersion due to migration of thermally activated oxygen vacancies at higher temperature above 175 8C. The activation energy calculated from the a.c. conductivity is 0.63 eV.  2003 Elsevier B.V. All rights reserved. Keywords: Laser ablation; Phase transition; Ferroelectric properties; Antiferroelectric PLZT thin film 1. Introduction The antiferroelectric phase can spontaneously be polarized into a ferroelectric phase by a sufficient application of electric field, since the associated free energy difference between the two phases was small enough to be excited by an external field w1x. Such field-induced phase transition properties in antiferroelec- tric compositions could be utilized for the high charge storage devices and micro actuator applications w2,3x. The La-modified lead zirconate titanate crystalline solution series, (Pb La )(Zr Ti )O wdesignated as 1yx x 1yy y 3 PLZT x y(1yy) yyx ceramics, was first investigated by Haertling w4x in the early 1970s. La doping effect into the Pb(Zr Ti )O (PZT) material was found to lead x 1yx 3 the dispersion behavior in both the ferroelectric rhom- bohedral and tetragonal states, and to increase the stability range of the antiferroelectric orthorhombic state on the Zr-rich side of the phase diagram w5,6x. In the antiferroelectric PLZT ceramics, the La impurities effect *Corresponding author. Tel.: q82-52-259-2323; fax: q82-52-259- 1693. E-mail address: kimiw@mail.ulsan.ac.kr (I.W. Kim). w7x, field induced polarization switching mechanism w5x, field induced strain properties w8x, the coexistence of incommensurate antiferroelectric and relaxor-like feroe- lectric phases w9x were observed for x y95y5 composition in the La yZr yTi ratio. La impurities in the PLZT materials were found to suppress long-rang ferroelectric order, however, the normal mm-sized ferroelectric domains did not break apart into an ensemble of polar nanodomains with increasing La content w10x. Handerek et al. w11x reported dielectric, pyroelectric and thermally stimulated depolarization current investigations for PLZT 100x y95y5 ceramics for 0.5-x-4.0 at.%. They observed relaxor like dielectric dispersion (10–10 Hz) 4 at temperature above that of the dielectric maxima. They attributed this abnormal behavior due to space-charge- induced polarization by mobile ionic defects. However, detailed phase relations on La doping were not reported. Though there were numerous reports on donor modi- fied Pb-based ferroelectric compositions such as lead zirconate titanate thin films, only little experiments were conducted on dielectric and hysteresis properties of donor modified antiferroelectric thin films w12,13x. Recently, a drive toward the antiferroelectric thin film,