Effects of bottom electrodes (Pt and IrO2) on physical and electrical properties of Bi4-xLaxTi3O12 (BLT) thin film

Bi3.35La0.85Ti3O12 (BLT) thin (90nm) films were prepared on Pt (200nm) and IrO2 (200 nm) electrodes by metalorganic decomposition (MOD) method, and crystallized by rapid thermal annealing (RTA) and the subsequent furnace annealing. BLT films were c-axis oriented on both electrodes irrespective of RTA temperature (600 and 700°C). However, the degree of c-axis orientation was much higher on IrO2 than on Pt, and significantly reduced only on Pt with decreasing RTA temperature. This result was related to the different stress of BLT film which is negligible on Pt, but 500 MPa (tensile) on IrO2 in the RTA temperature range of 600-700°C. The crystalline orientation of BLT film directly affected switching polarization (P*-P∧) which had much smaller value of 5 μC/cm2 on IrO2 than 12 μC/cm2 on Pt, and was increased to 16 μC/cm2 only on Pt with the decrease of RTA temperature. On the other hand, leakage characteristics were not changed with bottom electrode materials.