Preparation and Dielectric Properties of SrBi2Ta2O9 Thin Films by Sol-Gel Method

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Abstract
Ferroelectric Sr0.7Bi2.2Ta2O9 (SBT) thin films were prepared on Pt/Ti/SiO2/Si substrates at 800° C by sol-gel method. The means of preparation of solutions of SBT precursors and the addition of acetylacetone to the alkoxides affected the crystal orientation and the microstructure of the films. The (00 l ) preferred orientation degree of SBT thin films varied from 0 to 80%. Thin films of SBT with a highly preferred (00 l ) orientation exhibited grain structure resembling a stone wall, while those randomly-oriented with a high (105) diffraction intensity exhibited a rod-like grain structure. The SBT thin films with a random orientation exhibited values of ε r of 90, P r of 6.5 µ C/cm2 and E c of 80 kV/cm, while those with a (00 l ) orientation degree of 80% exhibited values of ε r of 78, P r of 1.6 µ C/cm2 and E c of 110 kV/cm. The (00 l ) preferred orientation was associated with the deterioration of ferroelectric properties.