Electrical Properties of Bi_4-<i>x</i>La_<i>x</i>Ti₃O₁₂Ferroelectric Thin Films Prepared by Metalorganic Decomposition Method

Abstract

Bi4-xLaxTi3O12 (BLT) ferroelectric thin films were prepared on a Pt/TiOx/SiO2/Si substrate using metalorganic decomposition (MOD) method, and their electrical properties were evaluated with thickness, composition and crystallization annealing temperature. Irrespective of the preparation conditions, BLT films were c-axis oriented, and had a dense surface morphology without pore to produce smooth Pt/BLT/Pt interfaces of capacitor. The film thickness was controlled as 90 nm to obtain a low coercive voltage (2Vc) without the problem of capacitor short-fail. The proper composition of Bi3.35La0.85Ti3O12 was selected for the largest switching polarization (P*-P∧), good fatigue endurance and a low leakage current density (JL). After crystallization annealing at 700°C, the optimized film of 90 nm Bi3.35La0.85Ti3O12 showed the good electrical properties, such as 2Vc of 2.0 V, P*-P∧ of 13 µC/cm2, JL of 1×10-6 A/cm2 at a applied voltage of 3 V and no polarization loss up to 1×1011 fatigue cycles, for ferroelectric random access memory (FeRAM) application.