Non-lead Ce: Na0.5Bi0.5TiO3–BiFeO3 solid solution thin film with significantly reduced leakage current and large polarization

The preferentially (100)-oriented 0.9Na0.5Bi0.5TiO3–0.1BiFeO3 (NBT–BFO) solid solution thin films with and without Ce substitution were grown on a LaNiO3(100)/Si substrate via a metal organic decomposition method. The effects of Ce doping on the crystalline structure, leakage current and ferroelectric property of NBT–BFO thin film were investigated. The diffraction peaks of NBT–BFO shift to higher diffraction angle as a result of shrinkage in the unit-cell volume by Ce substitution. At higher electric fields, the NBT–BFO film presents Poole–Frenkel emission consistent with the high leakage current, whereas in the Ce-doped NBT–BFO film, the dominant mechanism is changed to space-charge-limited conduction, and the leakage current density is reduced by two orders of magnitude. Compared with rounded ferroelectric polarization hysteresis loops of NBT–BFO film, substantial enhancement of ferroelectricity has been achieved in Ce-doped NBT–BFO film, with a remanent polarization (Pr) of 32.3 μC/cm2. The capacitance–voltage curves of Ce-doped NBT–BFO film show butterfly shape, and the degree of ferroelectricity is enhanced more and more with increasing applied voltage.