Study of dielectric and pyroelectric properties of sol-gel derived BST thin films

(Ba,Sr)TiO3 (BST) thin films have received considerable interest in recent years due to their many attractive properties like high dielectric constant, high dielectric breakdown strength and high pyroelectric coefficent. These films have been identified as promising material for several applications such as ferroelectric non-volatile memories and uncooled infrared focal plane arrays [UFPAs]. Barium strontium titanate (Ba 0.75 Sr 0.25 TiO3) thin films of thickness 0.5 mu m have been deposited on Pt/TiO2/SiO2/Si substrate by sol-gel spin coating method. The glancing angle X-ray diffraction of these films sintered at 700 degrees C in air shows polycrystalline nature. Dielectric constant (epsilon r ) and dielectric loss (tan delta) of the film measured at 1 KHz are found to be 400 and 0.02 respectively. The ferroelectric phase has been confirmed from the C-V and P-E studies. After poling the sample by corona charging technique, the pyroelectric coefficient at room temperature was found to be order of 10 -8 C/cm(2) K.