Formation and properties of SrBi2Ta2O9 thin films

Layered structure SrBi2Ta2O9 thin films were grown on Pt/Ti/Si/SiO2 substrates by laser ablation. The films were deposited at temperatures ranging from 500 to 750 °C and characterized for their phase formation, morphology, surface composition, and ferroelectric properties. Although crystalline phase formation was observed at temperatures as low as 500 °C, well defined saturated hysteresis loops were observed only in films deposited at temperatures of 700 °C or above. The transition in ferroelectric properties between 650 and 700 °C was associated with a change in orientation and grain size. The orientation of the films changed from highly c-axis oriented at 650 °C to randomly polycrystalline at 700 °C, while the grain size of the films increased from an average value of 80 nm (at 650 °C) to 160 nm (at 700 °C). An understanding of process-structure relationships is required in order to fabricate high quality films at lower temperatures.