Enhanced ferroelectric properties of vanadium doped bismuth titanate (BTV) thin films grown by pulsed laser ablation technique Ayan Roy Chaudhuri, Apurba Laha, S.B. Krupanidhi * Materials Research Centre, Indian Institute of Science, Bangalore 560 012, India Received 29 September 2004; accepted 25 October 2004 by C.N.R. Rao Available online 7 January 2005 Abstract Bi 3.99 Ti 2.97 V 0.03 O 12 (BTV) thin films were grown by pulsed laser deposition at substrate temperatures ranging between 650 and 750 8C. The structural phase, and orientation of the deposited films were investigated in order to understand the effect of the deposition parameters on the properties of the BTV films. As the substrate temperature was increased to 700 8C, the films started showing a tendency of assuming a c-axis preferred orientation, while at lower temperatures polycrystalline films were formed. The Au/BTV/Pt capacitor showed an interesting dependence of the remnant polarization (P r ) as well as dc leakage current values on the growth temperature. The film deposited at 675 8C showed a very large 2P r of 42 mC cm K2 , which is the largest for BTV thin films among the values reported so far. q 2005 Elsevier Ltd. All rights reserved. PACS: 77.80.Ke Keywords: A. BTV thin films; B. Laser ablation; D. Remnant polarization; D. Electrical properties 1. Introduction Research in the field of ferroelectric thin films is widely focused on the application of non-volatile random access memories (NVRAMs), sensors, transducers, actuators utilizing their low power consumption, high-speed readout, remote sensing ability and non-volatility [1,2]. Lead zirconate titanate (PZT) was the first generation candidate in this field, which had advantages of low crystallization temperature and large remnant polarization. However, PZT capacitors with metal electrodes (e.g. Pt) in general showed a reduction of polarization (fatigue) with the repetitive polarity switching (after 10 6 –10 7 cycles) [3,4], which limits their application in memory devices. Moreover, use of Pb based materials is currently considered eco-non-friendly. So, in addition to the challenges posed by the fatigue problem, the worldwide concern about environmental problems opened a renewed quest for lead free oxide for this kind of applications. Strontium bismuth tantalate (SBT) appeared as a second-generation material, which was proposed to overcome the fatigue problem [5]. But it also has a drawback of low remnant polarization and higher processing temperature compared to PZT thin films. Bismuth titanate (BIT) is a typical bismuth-layer ferroelectric material with structure related to SBT [6] which can be deposited at temperatures lower than SBT and has very large spon- taneous polarization along a-axis (P s w50 mC cm K2 ) [7]. However, the thin films [8] and ceramics [9] of BIT suffer from high leakage current and fatigue [10]. Recently, thin films of lanthanum-substituted bismuth titanate, Bi 3.25 La 0.75 Ti 3 O 12 (BLT) were reported to have higher 2P r of 24 mC cm K2 and fatigue endurance up to 10 10 read–write cycles [11]. The leakage current property of the BIT system was assumed to be due to the volatility of Bi 3C ions accompanied by oxygen vacancy. La 3C having ionic radius (1.06 A ˚ ) very close to that of Bi 3C (1.02 A ˚ ), it replaces Bi 3C 0038-1098/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ssc.2004.10.035 Solid State Communications 133 (2005) 611–614 www.elsevier.com/locate/ssc * Corresponding author. Fax: C91 80 2360 0085. E-mail address: sbk@mrc.iisc.ernet.in (S.B. Krupanidhi).