Investigation of the structural and electrical properties of Sr<inf>1-x</inf>Bi<inf>2.2</inf>Ta<inf>2</inf>O<inf>9</inf> thin films with deficient Sr contents

Abstract

Strontium bismuth tantalate Sr1-xBi2.2Ta2O9 (SBT, x = 0, 0.1, 0.2, 0.3, 0.4, 0.6) thin films with deficient Sr contents were prepared at 750 °C on Pt/TiO2/SiO2/Si substrates using metalorganic decomposition (MOD) spin-on technique. Effect of Sr deficiency compositions on the structural and electrical properties were investigated by means of X-ray diffraction (XRD), inductively coupled plasma (ICP) analyses, electronic probe microanalyses (EPMA), atomic force microscope (AFM), scanning electron microscope (SEM) and electrical measurements. The XRD results indicate the films with Sr deficiency content at 40% and below have layered perovskite structure with the distorted lattice. For films with 60% deficient Sr, the layered structure cannot be formed. SEM and AFM micrograph shows the surface morphology is very sensitive to the Sr deficiency. With increasing the Sr deficiency to 40% and above, the films exhibit the extremely inhomogeneity and poor crystallinity. The remnant polarization (Pr) gradually reduces with Sr deficiency. This is attributed to the distorted layered structure and the formation of amorphous phase. In summary, SrBi2.2Ta2O9 is found to be the optimum composition with respect to grain size, morphology, and electrical properties.