Control of Ferroelectric and Dielectric Properties of Undoped, Fe, and Nb-Doped Single-Crystalline (001) Oriented Pb (Zr0.5Ti0.5) O3 Thin Films

Abstract

While several factors that influence the properties of ferroelectric devices have been extensively studied in bulk ceramics and
polycrystalline thin films, limited is known about the same on single crystalline thin films which have great potential in memory and energy applications. This knowledge gap is largely due to the limited availability of substrates with lattice parameters suitable for
supporting high-quality epitaxial growth. In this study, undoped, Fe- doped, and Nb-doped (001)-oriented Pb(Zr₀.₅Ti₀.₅)O₃ thin films were
deposited using pulsed laser deposition, each with a SrRuO₃ bottom electrode and a PrScO₃ substrate. The doping concentration used is 1% for both Fe and Nb. The effect of the bottom electrode work function becomes less important as the thickness increases regardless of the nature of doping. The remanent polarization of undoped, Fe-doped, and Nb-doped PZT 50/50 films are 61, 21, and 35 μC/cm2 respectively. Measured higher values of remanent polarization suggest that at 150 nm thickness, single crystalline thin films behave as free single crystal whereby the effect of both the defects and substrate clamping is not significant. Measured dielectric permittivity values are 653, 207, and 357 for undoped, Fe-doped, and Nb-doped PZT 50/50 films respectively, which are relatively lower than those of bulk and thin films reported in the literature. The study has revealed that in monocrystalline thin films, the effect of substrate clamping on the dielectric properties is potentially dominant as compared to that of domain wall pinning by defects. Furthermore, the extrinsic contribution is proposed to be the dominant mechanism as evident from the dielectric loss values.