F.J. Geng

Enhanced electrical properties in Bi(Fe0·95Mn0·05)O3 modified Na0·5Bi0·5TiO3 thin film

Abstract 0·7Na0·5Bi0·5TiO3–0·3Bi(Fe0·95Mn0·05)O3 (NBT–BFOMn) and (Na0·5Bi0·5)TiO3 (NBT) thin films were fabricated on LaNiO3(l 00)/Si substrate by metal organic decomposition. Both films crystallise into the single perovskite structures with strong (l 00) diffraction peaks. The leakage current of NBT–BFOMn can be suppressed due to the decrease in the content for oxygen vacancies and the formation of defect complexes. Compared with the round shaped polarisation–electric field loop for pure NBT, much improved ferroelectric property with a remnent polarisation Pr of 28 μC cm−2 and coercive field Ec of 152 kV cm−1 at 630 kV cm−1 has been obtained for NBT–BFOMn thin film. In addition, the higher change of relative dielectric content ϵr variation versus voltage indicates the enhancement in the ferroelectric nature of NBT–BFOMn thin film. The ϵr and dissipation factor tanδ on frequency for NBT–BFOMn show small dispersion tendency with ϵr of 370 and tanδ of 0·167 at 100 kHz.

Site engineering in chemical solution deposited Na1/2Bi1/2TiO3 thin films using Mn acceptor

A series of Mn doped Na1/2Bi1/2TiO3 (NBT) thin films with dopant concentrations from 0 to 4 at% (NBTMn x , x = 0, 0.01, 0.02, 0.04) were fabricated on the indium tin oxide/glass substrates by chemical solution deposition. The effects of Mn doping content on crystalline, ferroelectric and dielectric properties were investigated. All thin films exhibit phase-pure polycrystalline perovskite structures. For the insulating measurement, at low electric field, space charge limited conduction or a grain boundary limited behavior is responsible for the leakage behavior of NBTMn x thin films, whereas at the high electric field, the dominant mechanism is changed to the interface-limited Fowler–Nordheim tunneling except NBTMn0.04. The leakage current density is reduced by more than three orders of magnitude in NBTMn0.02 compared with that of NBT thin film. Also, the enhanced ferroelectric properties of NBTMn0.02 thin film can be observed in polarization–electric filed hysteresis loop with P r of 38 μC cm−2, which is consistent with the result of the normalized capacitance–voltage curve. The dielectric constant and dissipation factor of NBTMn0.02 thin film are 501 and 0.04, respectively at 100 kHz. These electrical property improvements are attributed to the decrease of oxygen vacancy-induced leakage current.