Strain-enhanced Dielectric and Ferroelectric Properties of Pb(Zr_(0.8)Ti_(0.2))O_3/Pb(Zr_(0.2)Ti_(0.8))O_3 Multilayer Thin Films Without Buffer Layers

摘要

A series of Pb(Zr_(1-x)Ti_x)O_3 (PZT) multilayer films were deposited on Pt/Ti/SiO_2/Si substrates by rf magnetron sputtering. All the films comprise 6 periodicities of Pb(Zr_(0.8)Ti_(0.2))O_3/Pb(Zr_(0.2)Ti_(0.8))O_3 with the periodicity thickness of 133 nm, but the layer thicknesses of rhombohedral phase (d_R) and tetragonal phase (d_T) in one periodicity are varied. The electric properties of the films were investigated as a function of dR/dT. The films with dR/dT=1:3 possess enhanced dielectric and ferroelectric properties: dielectric constant epsilon_r=328 at 10 kHz with a reduced dielectric loss tg delta=0.0098 and sharply enhanced remanent polarization P_r=32.6 mu C/cm2. The enhanced properties of the multilayer films were resulted from the presence of interfaces and strain between the rhombohedral and tetragonal phase layers. The mechanism of the strain-enhanced electrical properties was also discussed. This design of multilayer structure can tailor the electric properties and it demonstrates a route to a ferroelectric multilayer film devices.