Low temperature preparation of fatigue free Bi/sub 4/Ti/sub 3/O/sub 12/ thin films by MOCVD and their electrical properties

We have investigated the low temperature MOCVD method to form Bi/sub 4/Ti/sub 3/O/sub 12/ thin films with suitable electrical properties for nonvolatile ferroelectric memory applications. An ultra thin double buffer layer (5nm-Bi/sub 4/Ti/sub 3/O/sub 12//5nm-TiO/sub 2/) was used to control the crystallization and a fine grain structure of Bi/sub 4/Ti/sub 3/O/sub 12/ at a low growth temperature was obtained. 100 nm-Bi/sub 4/Ti/sub 3/O/sub 12/ thin films grown at 400/spl deg/C showed an excellent smooth surface morphology and had good electrical properties, namely, remanent polarization, Pr=11 /spl mu/C/cm/sup 2/, coercive field, Ec=90 kV/cm and low leakage current, IL=7/spl times/10/sup -9/ A/cm/sup 2/ at 3 V. Additionally, for the first time, fatigue free property was confirmed up to 1/spl times/10/sup 12/ switching cycles. Furthermore, it was found that the Bi/sub 4/Ti/sub 3/O/sub 12/ thin films with a bismuth rich composition showed the (117) preferred orientation and a very large Pr of 23 /spl mu/C/cm/sup 2/.