| 초록 |
Bismuth titanate ( $Bi_4Ti_3O_{12}$ , BIT) thin film has been studied intensively in the past decade due to its large remanent polarization, low crystallization temperature, and high Curie temperature. Substitution of various trivalent rare-earth cations (such as $La^{3+}$ , $Nd^{3+}$ , $Sm^{3+}$ and $Pr^{3+}$ ) in the BIT structure is known to improve its ferroelectric properties, such as remanent polarization and fatigue characteristics. Among them, neodymuim-substituted bismuth titanate, ((Bi, Nd) $_4Ti_3O_{12}$ , BNT) has been receiving much attention due to its larger ferroelectricity. In this study, Ferroelectric $Bi_{3.3}Nd_{0.7}Ti_3O_{12}$ thin films were successfully fabricated by liquid delivery MOCVD process onto Pt(111)/Ti/ $SiO_2$ /Si(l00) substrates. Fabricated polycrystailine BNT thin films were found to be random orientations, which were confirmed by X-ray diffraction and scanning electron microscope analyses. The remanent polarization of these films increased with increase in annealing temperature. And the film also demonstrated fatigue-free behavior up to $10^{11}$ read/write switching cycles. These results indicate that the randomly oriented BNT thin film is a promising candidate among ferroelectric materials useful for lead-free nonvolatile ferroelectric random access memory applications. |
