Low temperature preparation of fatigue free Bi4Ti3 O12 thin films by MOCVD and their electrical properties

We have investigated the low temperature MOCVD method to form Bi ₄Ti₃O₁₂ thin films with suitable electrical properties for nonvolatile ferroelectric memory applications. An ultra thin double buffer layer (5nm-Bi₄Ti₃O₁₂/5nm-TiO₂) was used to control the crystallization and a fine grain structure of Bi₄Ti₃O₁₂ at a low growth temperature was obtained. 100 nm-Bi₄Ti₃O₁₂ thin films grown at 400°C showed an excellent smooth surface morphology and had good electrical properties, namely, remanent polarization, Pr=11 μC/cm², coercive field, Ec=90 kV/cm and low leakage current, IL=7×10^-9 A/cm² at 3 V. Additionally, for the first time, fatigue free property was confirmed up to 1×10¹² switching cycles. Furthermore, it was found that the Bi₄Ti₃O₁₂ thin films with a bismuth rich composition showed the (117) preferred orientation and a very large Pr of 23 μC/cm²