Structural and ferroelectric properties of r.f. magnetron sputtered SrBi2Ta2O9 thin films

Radio-frequency magnetron sputtering was used to deposit SrBi₂Ta₂O₉ ferroelectric thin films on Pt(111)/Ti/SiO₂/Si(100) substrates with 15% Bi₂O ₃ excess SrBi₂Ta₂O₉ ceramic target. Thin films were deposited at room temperature with argon pressures of 0.5~100 mTorr and sputtering power of 200 W. Deposited thin films were post-annealed at 800°C for 2 hours in O₂ atmosphere. Structural properties were investigated with X-ray diffraction techniques. And microstructures were observed by the scanning electron microscope. Crystal orientations and microstructures of the thin films were strongly affected by the argon pressures during the deposition. Ferroelectric properties of the Pt/SrBi₂Ta ₂O₉/Pt capacitors were obtained. The physical properties of the c-axis oriented and polycrystalline SrBi₂Ta ₂O₉ were compared. The c-axis oriented thin films show good ferroelectric properties, (P*_r-P^ˆ _r) and E_c were 10.4 μC/cm² and 50 kV/cm, respectively. And for the polycrystalline thin film, (P*_r -P^ˆ_r) and E_c were 6.5 μC/cm² and 43 kV/cm, respectively