Oriented growth of SrBi2Ta2O9 ferroelectric thin films

We report on the ferroelectric properties of c-axis oriented ferroelectric SrBi2Ta2O9 thin films. Pt/SrBi2Ta2O 9/Pt capacitors were grown on single crystal MgO (and/or SrTiO3) substrates using pulsed laser ablation. These substrates provide the necessary template for (100) texture in platinum due to their close lattice matching. This in turn facilitates the c-axis orientation in the ferroelectric films. The degree of orientation in the layered structure ferroelectric film was systematically varied from highly c-axis oriented to random polycrystalline by varying the growth conditions of the bottom metal electrode. The polarization and coercive field values were found to decrease with an increasing degree of c-axis orientation; while the randomly oriented films exhibited a remnant polarization of 5 μC/cm 2, a coercive field of 70 kV/cm, and a dielectric constant of 320, the c-axis oriented films exhibited very low polarization (∼1 μC/cm2), coercivity (22 kV/cm), and dielectric constant (∼200) values.