Properties of neodymium-doped Bi4Ti3O12 thin films for ferroelectric random access memory

The microstructure and ferroelectric properties of Neodymium-doped Bi4Ti3O12 (Bi1-xNdx)(4)Ti3O12 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 degrees 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 similar to 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 degrees C exhibited larger remament polarization (P-r) and lower coercive field (E-c). At the applied voltage of 5V, 2P(r) and E-c values was 45 mu C/cm(2) 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 10(11) switching cycles. It suggested that BNT films showed excellent polarization and fatigue properties, which could be used for FeRAM applications.