Chemical Processing and Dielectric Properties of Ferroelectric SrBi2Ta2O9 Thin Films

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Abstract
Ferroelectric SrBi2Ta2O9 (SBT) thin films were prepared on Pt/SiO2/Si substrates at 800° C by MOD and sol-gel methods. SBT thin films prepared by the MOD method using strontium 2-ethylhexanoate, bismuth 2-ethylhexanoate and tantalum ethoxide showed a fine-grained structure with grain sizes of about 130 nm. The SBT thin films with a thickness of 400 nm exhibited ε r of about 180, P r of about 4.5 µ C/cm2 and E c of 60 kV/cm. No fatigue was observed up to 109 switching cycles. On the other hand, in the sol-gel method, SBT thin films crystallized with a high (105) diffraction intensity at 650° C, but with a highly (00l) preferred orientation at 800° C. The thin films showed grain structure with grain sizes of 100–300 nm. The sol-gel-derived 390 nm-thick SBT films with random orientation exhibited ε r of about 100, P r of about 2.8 µ C/cm2 and E c of 108 kV/cm.