DI FERROELECTRIC PROPERTIES OF BISMUTH-BASED LAYERED FERROELECTRIC-FILMS FOR APPLICATION TO NONVOLATILE MEMORIES/

We have constructed Bi based layer structured Ferroelectric films and their superlattices by a pulsed laser deposition technique. The dielec tric constants along c-axis increase with increasing of the number of pseudo-perovskite layers between double Bi2O2 layers. Ferroelectricity appears along the c-axis direction only for the odd number of the per ovskite layers owing to the mirror symmetry in a crystal structure. Es pecially, the Bi2VO5.5, film shows an atomically flat surface, low die lectric constant of 30 and Ferroelectricity of P-r=3 mu C/cm(2) and E- c=16 kV/cm, respectively. This material is expected to the application for FRAMs.