Effects of annealing atmosphere on microstructure and ferroelectric properties of praseodymium-doped Bi4Ti3O12 thin films prepared by sol–gel method

Praseodymium-substituted bismuth titanate (Bi3.2Pr0.8Ti3O12, BPTO) thin films were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates by spin coating with a sol–gel technology and rapid thermal annealing. The effects of annealing atmospheres (vacuum, ambient atmosphere and oxygen) on the growth and properties of thin films were investigated. The results show that the intensity of the (117) diffraction peak of Bi3.2Pr0.8Ti3O12 film annealed in oxygen is stronger than those annealed in ambient atmosphere and vacuum. The XRD spectra demonstrated that a highly (117) orientation could be obtained when the Bi3.2Pr0.8Ti3O12 thin film was annealed in an oxygen-sufficient environment. The BPTO thin films annealed in oxygen atmosphere exhibits the maximum remanent polarization (2Pr) of 49 μC/cm2 and a low coercive field (2Ec) of 130 kV/cm, fatigue free characteristics up to ≧ 1011 switching cycles. These results indicate that the BPTO thin film is useful in nonvolatile ferroelectric random access memory applications.