Ferroelectric and dielectric behavior of heterolayered PZT thin films

Heterolayered Pb(Zr1-xTix)O-3 thin films consisting of different numbers of alternating Pb(Zr0.7Ti0.3)O-3 and Pb(Zr0.3Ti0.7)O-3 layers are studied. They exhibit (001)/(100) preferred orientation and dense microstructure when baked at 500 degrees C and then thermally annealed at 650 degrees C. They demonstrate a considerably low leakage current density in the order of 10(-7) A/cm(2). Their ferroelectric and dielectric properties are improved with increasing number of alternating Pb(Zr0.7Ti0.3)O-3 and Pb(Zr0.3Ti0.7)O-3 layers, thereby the six-heterolayered PZT thin film shows a much enhanced remanent polarization of 41.3 mu C/cm(2) and relative permittivity of 710 at 1 kHz. In fatigue test, a wake-up phenomenon is observed with the heterolayered films, where the degradation in switchable polarization is delayed. At elevated temperatures, the wake-up phenomenon was reduced, leading to fatigue degradation at a relatively lower number of switching cycles. The phenomenon is related to the injected electron causing oxygen vacancies, the accumulation of which impedes the domain switching.