摘要
用改进的溶胶一凝胶法制备光滑致密的预晶化铈（Ce）和锰（Mn）共掺钛酸锶钡（CeMn—SST）薄膜。电容－电压曲线表明，随着薄膜厚度的增加，综合介电性能大幅度改善，8层薄膜显示介电常数约为1300、低于0．007介电损耗、高于58％调谐率及接近180优质因子等优化介电性能，为主要沿（1101晶面层状生长的钙钛矿结构。
Smooth and dense preheated cerium （Ce） and manganese （Mn） codoped barium strontium titanate （CeMn-BST） films with various thicknesses were prepared by improved sol-gel method. Capacitance-voltage curves show that with increasing film thickness, combination of dielectric properties are significantly improved with optimized values of about 1300 moderate permittivity, less than 0.007 dielectric loss, more than 58% tunability and hence near 180 figure of merit （FOM） for eight-layer CeMn-BST film. The improved mechanisms for such excellent dielectric properties were investigated. XRD shows that the films layered-grow mainly along （110） orientation and exhibit ABO3 cubic perovskite structure. As film thickness increases, Ce3＋ and/or Mn2＋ ions showed doping modes from donor doping to acceptor doping, the crystallization of films is improved, but the average grain sizes of the films show gradually decreased trend from about 45 nm to 25 nm in terms of the intensities of （110） diffraction peaks. AFM indicates that the films become smoother with smaller roughness with increasing thickness. XPS reveals that the films reveal decreased non-perovskite structure, element core levels and Fermi levels with increasing thickness. Leakage current densities are significantly decreased almost at two orders of magnitude with increasing thickness. Pure BST films are compared.
