CaBi 4 Ti 4 O 15 thin film deposition on electroplated Platinum substrates using a sol-gel method
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1113-F03-27
CaBi4Ti4O15 thin film deposition on electroplated Platinum substrates using a sol-gel method Takeyasu Saito1, Yuichiro Hirota1, Mariko Ooyanagi1, Naoki Okamoto1, Kazuo Kondo1, Takeshi Yoshimura2 and Norifumi Fujimura2 1 Department of Chemical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan 2 Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan ABSTRACT CaBi4Ti4O15 growth on different Platinum substrates was carried out through a sol-gel method. Higher crystallization temperature and 20% excess Bi decreased pyrochlore contents in the CaBi4Ti4O15 films. Repetition through coating, calcination and crystallization decreased void formation on the surface. C-axis oriented thin film could be grown on sputtered platinum substrates with low Pt (200) orientation. On electroplated Pt substrates, (119) oriented CaBi4Ti4O15 thin film was grown, suggesting surface roughness of Pt substrates is a crucial factor for orientation control of sol-gel derived CaBi4Ti4O15 thin film. INTRODUCTION Ferroelectric random access memory (FeRAM) is one of the promising candidates for embedded nonvolatile memory, especially in applications where low power and high transaction rate are important as contactless smart cards, IC tags and so on [1-4]. The integration of FeRAM devices for mass production is still progressing, focusing on 0.13µm technologies, with introduction of the stacked ferroelectric capacitor cell [5-7]. However, FeRAM technology is still behind the scaling evolution of the standard CMOS. Aiming further scaling of FeRAM for sub 100nm technologies, the current strong concerns are single-mask etched stacked capacitor structure and fabrication of three-dimensional (3D) capacitors [8-10]. 3D capacitor-integration technology for larger memory size is the definitely crucial issue, however, more robust materials development without lead with immunity to complicated device fabrication processes and device function at higher operation temperature are also required. One of the promising candidates for replacing Lead Zirconium Titanate (PZT) is bismuth layerstructured ferroelectric (BLSF) which offers not only good ferroelectric properties but also high Curie temperatures. The general formula of BLSF is (Bi2O2)2+(Am−1BmO3m+1)2-, where A is a mono-, di- or trivalent cation (or combination thereof) allowing dodecahedral coordination and B is a transition metal cation with octahedral coordination, e.g. Ti4+, Nb5+, Ta5+ or W6+; m is the number of octahedral layers in the perovskite slab, which varies from 1 to 6 [11-16]. CaBi4Ti4O15 is a member of the Aurivillius family, (Bi2O2)2+(Am−1BmO3m+1)2-, which is characterized by high Curie temperature as 790°C [17]. This is very promising as high temperature operation devices [18-22], however, further crystallographic study to achieve enough ferroelectric or piezoelectric properties should be required. In this work, CaBi4Ti4O15 growth on different Platinum substrates was carried out throu
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