Dielectric properties of nanocrystalline Pb0.8Sr0.2TiO3 thin films at different annealing temperature

Nanocrystalline Pb0.8Sr0.2TiO3 (PST20) thin films have been synthesized by metallo-organic decomposition (MOD) technique and deposited on Pt/Ti/SiO2/Si substrates at different annealing temperatures of 550-750 deg C. The X-ray diffraction (XRD) confirms the distorted tetragonal perovskite phase in PST20 films. The average grain's size varies from 35 nm to 46 nm as the annealing temperature increases from 650 deg C to 750 deg C as revealed by atomic force microscopy. At 550 deg C, the film shows low crystallization with incomplete perovskite structure. The study of dielectric properties of PST20 films is aimed at electrically tunable applications and to observe ferroelectric behaviors of PST20 films. The film annealed at 650 deg C shows large dielectric constant and higher tunability than the films annealed at 550 deg C and 750 deg C. The values of dielectric constant and tan delta at 1 MHz are 272 and 0.005, respectively, and tunability is 66% for PST20 film annealed at 650 deg C. The dispersionless dielectric properties are observed up to high frequency 8 MHz. The results suggest that the growth of uniform, dense and nano-sized grains in PST film makes it suitable for higher frequency device applications and electrically tunable devices.