Appl. Phys. A 69, 55–61 (1999) / Digital Object Identifier (DOI) 10.1007/s003399900056 Applied Physics A Materials Science & Processing  Springer-Verlag 1999 Film structure and ferroelectric properties of in situ grown SrBi 2 Ta 2 O 9 films R. Dinu ∗ , M. Dinescu ∗ , J.D. Pedarnig, R.A. Gunasekaran ∗∗ , D. Bäuerle, S. Bauer-Gogonea, S. Bauer Department of Applied Physics, Johannes-Kepler University, Altenberger Str. 69, A-4040 Linz, Austria (Fax: +43-732/2468-9242) Received: 18 March 1999/Accepted: 19 March 1999/Published online: 5 May 1999 Abstract. Ferroelectric SrBi 2 Ta 2 O 9 (SBT) films were grown by pulsed-laser deposition (PLD) at different substrate tem- peratures and fluences. A correlation between film struc- ture and ferroelectric properties is established. The dielectric function ε ′ of thin SBT films shows a Curie–Weiss behavior well below the peak temperature T max and relaxor-like be- havior in the vicinity of T max . Domain walls have a strong influence on the dielectric and ferroelectric properties and on the polarization fatigue of SBT films below 100 ◦ C. The for- mation of ferroelectric phases is favored at lower substrate temperatures by incorporating Bi 2 O 3 template layers into the structure. PACS: 81.15.Fg; 68.55.-a; 77.80.-e Ferroelectric materials with layered-perovskite structures at- tracted considerable attention in the early sixties, but interest appeared to fade because of the relatively small piezoelec- tric coefficients [1–3]. Renewed interest grew in the early 90s because of the apparent similarities of their structure to that of Bi-based high-temperature superconductor compounds [4]. Recently, bismuth-based layered perovskites have been inves- tigated for nonvolatile ferroelectric random-access memories showing practically no polarization fatigue when subjected to electric field cycling [5], in contrast to lead zirconate titanate (PZT) which exhibits severe fatigue after 10 8 read–write cy- cles when deposited on metallic electrodes [6]. The most promising compound among the Bi-based layered perovskites is SrBi 2 Ta 2 O 9 (SBT). Recent studies demonstrated little po- larization fatigue (up to 10 12 cycles), low imprint tendency, and low leakage currents [5]. SBT thin films have been grown by different techniques, such as liquid-phase deposition [5–7], radio-frequency mag- netron sputtering [8], metal-organic chemical vapor deposi- tion (MOCVD) [9], plasma-enhanced MOCVD [10], as well ∗ On leave from IFA, National Institute of Lasers, Plasma and Radiation Physics, P.O.Box MG-16, RO-76900, Bucharest V, Romania. ∗∗ Present address: Institute for Micromanufacturing, Louisiana Tech Uni- versity, P.O. Box 10137, Ruston, LA71272, USA. as pulsed-laser deposition (PLD) [11, 12]. In order to obtain well-crystallized SBT films, most of these techniques require post-annealing for typically 1.5–2 h at temperatures in the range 700–800 ◦ C. For silicon technology, such temperatures are impractical. Among the different techniques employed, PLD is ideally suited for oriented growth of multicomponent oxides, because complex target compositions can be stoichiometrically repro- duced at the substrate [13]. Not much is known on temperature-dependent dielec- tric and ferroelectric properties of thin SBT films [14]. Temperature-dependent studies may yield information on do- main wall motion, pinning and unpinning, as direct nanoscale- size imaging of domains is a challenging task for thin SBT films showing small longitudinal piezoelectric (d 33 ) coeffi- cients [15]. Additionally, temperature-dependent measure- ments may shed light on the nature of the ferroelectric phase transition of SBT films (normal or relaxor-like). In the present paper we report on PLD of SrBi 2 Ta 2 O 9 films and Bi 2 O 3 /SrBi 2 Ta 2 O 9 /Bi 2 O 3 multilayers on Pt/Ti/ SiO 2 -coated Si(100) wafers at different substrate tempera- tures and laser fluences. The correlation between deposition parameters, film structure, and ferroelectric properties is dis- cussed, as well as the nature of the phase transition in the vicinity of the dielectric anomaly. Domain wall effects on the dielectric function, remanent polarization, and polariza- tion fatigue are discussed in order to show that a complete characterization of ferroelectric thin films requires a whole bundle of structural and electrical investigations. 1 Experimental SBT targets were prepared by mixing and calcinating pow- ders of SrCO 3 , 10% enriched Bi 2 O 3 and Ta 2 O 5 at 850 ◦ C, and subsequent sintering of the pressed pellets at 900 ◦ C for 24 h in air. Bi-enriched targets (SrBi 2.2 Ta 2 O 9 ) have been used in order to compensate the Bi loss during film deposi- tion. Pt/Ti/SiO 2 /Si(100) structures were used as substrates. 2000-Å-thick Pt electrodes were deposited at 550 ◦ C by elec- tron beam evaporation. In order to improve the Pt adhesion to