Dielectric properties of Pb(Zr20Ti80)O3/Pb(Zr80Ti20)O3 multilayered thin films prepared by rf magnetron sputtering

Abstract

A series of Pb(Zr,Ti)O3 (PZT) films with tetragonal/rhombohedral multilayered structures has been grown on Pt/TiO2/SiO2/Si substrates by rf magnetron sputtering at a relative low temperature. All the films comprise 12 periodicities of Pb(Zr20Ti80)O3/Pb(Zr80Ti20)O3 in constant thickness of 40 nm, but the layer thicknesses of tetragonal phase (dT) and rhombohedral phase (dR) in one periodicity are varied. The electric properties of the films are investigated as a function of dT/dR from 10/30 to 35/5. An enhanced dielectric property is observed in the multilayered films. Especially, a optimal value of dT/dR=30/10 is obtained, where the dielectric constant reaches maximum value of 469 at 100 kHz with a loss tangent of 0.037, and the dielectric constant is about five times that of the single tetragonal phase PZT film formed under the identical condition. Moreover, the polarization also increases in the multilayered films, and remarkably, the film of 30/10 exhibits larger remanent polarization, lower coercive voltage, and more symmetric hysteresis than the other films. The enhancement of dielectric properties is attributed to the presence of interfaces between the tetragonal and the rhombohedral phase layer. This study suggests that the design of the multilayered PZT film capacitor with tetragonal and rhombohedral phase should be an effective way to enhance the dielectric and ferroelectric performance in devices.