Ultra-thin fatigue-free Bi4Ti3O12 films for nonvolatile ferroelectric memories

We have developed a new low temperature growth technique for Bi4Ti3O12 thin films using a MOCVD method in which an ultra-thin double buffer layer (5-nm thick Bi4Ti3O12/5-nm thick TiO2) is used to control the crystallization and fine grain structure. The 100-nm thick Bi4Ti3O12 thin films fabricated at 400 degrees C showed an extremely smooth surface morphology and good electrical properties, namely, a large remanent polarization of P-r = 11 mu C/cm(2), a coercive field of E(c) = 90 kV/cm and a low leakage current I-L = 7 x 10(-9) A/cm(2) at 3 V. Moreover, we successfully fabricated 50-nm ultra thin Bi4Ti3O12 films with P-r = 9 mu C/cm(2) and E(c) = 120 kV/cm at 3 V. For the first time, the fatigue free property, which is very important for nonvolatile ferroelectric memory (NVFRAM) applications, was confirmed up to 1 x 10(12) switching cycles.