PROPERTIES OF NEODYMIUM-DOPED Bi 4 Ti 3 O 12 THIN FILMS FOR FERROELECTRIC RANDOM ACCESS MEMORY

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The microstructure and ferroelectric properties of Neodymium-doped Bi4Ti3O12 (Bi1-xNd x )4Ti3O12 were studied in the paper. Bi3.15Nd0.85Ti3O12 (BNT) polycrystalline thin films were successfully prepared on Pt/Ti/SiO2/Si (100) substrates using Sol-Gel technique. The 6-layer BNT thin films with only one phase were produced at 750°C. BNT thin films showed certain c-axis orientation growth and the c-orientation ratio was about 72.5%. The thickness of one layer film was about 20 ∼ 22 nm. BNT thin films was composed of grains of 250 nm in diameter and the surface roughness (Ra) of the film was about 1.25. Pt/BNT/Pt capacitor annealed at 750°C exhibited larger remament polarization (Pr) and lower coercive field (Ec). At the applied voltage of 5V, 2Pr and Ec values was 45 μ C/cm2 and 80 kV/cm, respectively. The fatigue characteristics of Pt/BNT/Pt capacitor indicated that BNT thin films exhibited little change in polarization up to 1011 switching cycles. It suggested that BNT films showed excellent polarization and fatigue properties, which could be used for FeRAM applications.