Structural and electrical properties of (Bi, La)₄Ti₃O₁₂ thin films with a thin Bi₂O₃ top-layer prepared by a chemical solution deposition method

Abstract

Fatigue-free ferroelectric (Bi, La)₄Ti₃O₁₂ (BLT) thin films with a Bi₂O₃ top-layer were prepared on Pt/Ti/SiO₂/Si substrates by a chemical solution deposition method. The BLT films with a thin Bi₂O₃ top-layer or those without a Bi₂O₃ layer had a highly c-axis oriented growth. It was found that the use of the Bi₂O₃ top-layer improved significantly the P-E hysteresis loops of BLT thin films. The remanent polarization (2P_r) and coercive field (E_c) values of BLT films without a Bi₂O₃ layer and those with a Bi₂O₃ top-layer annealed at 750°C were 10.8 and 29.12 μC/cm², 79.0 and 74.5 kV/cm at an applied electric field of 350 kV/cm, respectively. The capacitor with Bi₂O₃ top-layer showed good fatigue-free polarization characteristics and retention properties.