Phase development in pulsed laser deposited Pb[Yb 1/2 Nb 1/2 ]O 3 -PbTiO 3 thin ®lms V. Bornand * , S. Trolier-Mckinstry The Pennsylvania State University, Department of Materials Science and Engineering, Materials Research Laboratory, University Park, PA 16802-4801, USA Received 10 August 1999; received in revised form 16 February 2000; accepted 16 February 2000 Abstract (1 2 x) Pb[Yb 1/2 Nb 1/2 ]O 3 2x PbTiO 3 (PYbN-PT, x  0:4 and 0.5) / SrRuO 3 (SRO) heterostructures have been prepared by pulsed laser deposition (PLD) on k100l pc -oriented LaAlO 3 (LAO) substrates (the subscript pc refers here to the pseudo-cubic perovskite subcell). Careful control of both lead volatilization and pyrochlore formation during the growth appears to be essential to obtain perovskite PYbN-PT thin ®lms with good crystalline, electrical and ferroelectric properties. By utilizing PbO-enriched ceramic targets and adjusting deposition parameters such as the laser frequency, the chamber pressure, the target to substrate distance and/or the substrate temperature, high-quality thin ®lms can be successfully grown with a single out-of-plane k001l pc orientation and an in-plane heteroepitaxial arrangement of [110] pc PYbN-PT // [110] pc . SrRuO 3 . When processed in the 560±6608C temperature range, with a dynamic O 3 /O 2 pressure of 300±400 mTorr and relatively high laser repetition rates, PYbN-PT ®lms exhibit improved ferroelectric properties. The typical values of the remanent (P r ) and saturation (P s ) polarizations increase up to 50 and 80 mC/cm 2 , respectively. q 2000 Published by Elsevier Science S.A. All rights reserved. Keywords: Laser ablation; Ferroelectric thin ®lm heterostructures; Epitaxy; Lead ytterbium niobate - lead titanate 1. Introduction Ferroelectric ®lms can display a wide range of dielectric, ferroelectric, piezoelectric, electrostrictive and pyroelectric characteristics [1,2]. The potential utilization of these prop- erties in a new generation of devices has motivated intensive studies on the synthesis, characterization and processing- microstructure-property relationships of such ®lms during the past 20 years. In particular, advances in ferroelectric and piezoelectric thin ®lm deposition technology have gener- ated a considerable interest within the electronic materials community. Originally directed towards memory applica- tions it is now rapidly spreading to other areas such as the biomedical, automotive, computer and communication industries [3±6]. Many ferroelectric materials under research for thin ®lm microelectromechanical systems (MEMS) are perovskite compounds, such as the morphotropic phase boundary Pb[Zr 12x Ti x ]O 3 (PZT) [7]. Though successful devices using PZT have already been demonstrated, the piezoelec- tric properties at best approach those of hard PZT ceramics. Substrate clamping and reduction of the extrinsic contribu- tions to the piezoelectric coef®cients are, at least in part, responsible for the disparities between bulk ceramic and thin ®lm characteristics [8,9]. Given the property limitations of PZT thin ®lms, alternatives, including Pb[B 0 B 00 ]O 3 and (1 2 x) Pb[B 0 B 00 ]O 3 2x PbTiO 3 materials, are particularly interesting [10,11]. The large polarization and permittivity values of such complex perovskites make them promising candidates for microeletromechanical systems. Important relaxor systems which show enhanced piezoelectric activity are (1 2 x) Pb[Zn 1/3 Nb 2/3 ]O 3 2x PbTiO 3 (PZN-PT) [12] and (1 2 x) Pb[Mg 1/3 Nb 2/3 ]O 3 2x PbTiO 3 (PMN-PT) [13]. As shown by Park et al. [13,14], large piezoelectric coef®cients (in excess of 2500 pC/N) can be observed along the k001l- direction in rhombohedral single crystals. Similarly, k001l heteroepitaxial PMN-PT ®lms deposited on SrRuO 3 / LaAlO 3 substrates also show enhanced piezoelectric coef®- cients relative to PZT ®lms of the same thickness [15,16]. For MEMS, the major challenge is to prepare these materi- als as `single crystal' epitaxial thin ®lms between metallic electrodes and integrate them so that their ferroelectric and electromechanical properties can be used in piezoelectric devices. When dealing with ferroelectric MEMS, both the choice Thin Solid Films 370 (2000) 70±77 0040-6090/00/$ - see front matter q 2000 Published by Elsevier Science S.A. All rights reserved. PII: S0040-6090(00)00927-5 www.elsevier.com/locate/tsf * Corresponding author. Tel.: 133-467-14-33-43; fax: 133-467-14-42- 90. E-mail address: vbornand@lpmc.univ-montp2.fr (V. Bornand).