Analysis of the dependence of ferroelectric properties of strontium bismuth tantalate (SET) thin films on the composition and process temperature

Ferroelectric properties, crystal structure and microstructures were examined for various Sr/Bi/Ta atomic ratio strontium bismuth tantalate (SET) films prepared by metalorganic decomposition at 700 and 800 degrees C. The 20% Sr-deficient and 10% Bi-excess (0.8/2.2/2) composition showed maximum remanet polarization (P-r) values for both 700 and 800 degrees C crystallization temperatures. From TEM analysis, the P-r dependence on composition variation around the stoichiometric 1/2/2 composition was related to grain size and volume of voids. The effect of postannealing after Pt top electrode fabrication was also studied. On the films prepared at 800 degrees C, postannealing markedly reduced the capacitor shorting rate. This was attributed to recrgstallization of the Pt top layer, based on SEM analysis of the Pt layer and the Pt/SBT inter face.