Ferroelectricity of Sol-Gel Thin Film Multilayer Heterostructures of Modified PbTiO_3 onto Si-Based Substrates

摘要

In the last few years, a great interest has been developed on the modified-PbTiO_3 multilayer heterostructures due to their enhanced dielectric, ferroelectric and pyroelectric properties. Multilayer thin films were prepared in this work by multiple deposition and crystallization of(Pb_(0.76)Ca_(0.24))TiO_3 (PTC) and (Pb_(0.88)La_(0.08))TiO_3 (PTL) air stable solutions prepared by the diol sol-gel route. The films were deposited onto Pt/TiO_2/SiO_2/(100)Si substrates subjected to a thermal treatment at 650 deg C during 30 min before the deposition of the films. Two types of heterostructures were prepared: PTC/PTL/PTC and PTL/PTC/PTL. X-ray diffraction (XRD) was carried out, to determine the structural and textural characteristics of the films. The origin of the texture is discussed. The ferroelectric character of the films was also analyzed by measurement of the ferroelectric hysteresis loops and the temperature dependence of the permittivity.