Di/Ferroelectric Properties of Bismuth Based Layered Ferroelectric Films for Application to Non-Volatile Memories

摘要

We have constructed Bi based layer structured ferroelectric films and their superlattices by a pulsed laser deposi- tion technique. The dielectric constants along c-axis increase with increasing of the number of pseudo-perovskite layers between double Bi_2O_2 layers. Ferroelectricity appears along the c-axis direction only for the odd number of the perovskite layers owing to the mirror symmetry in a crystal structure. Especially, the Bi_2VO_5.5 film shows an atomically flat surface, low dielectric constant of 30 and ferroelectricity of P_r = 3 μC/cm~2 and E_c=16 kV/cm, respectively. This material is expected to the application for FRAMs.