Electrical properties of chemically derived (Pb,La)TiO/sub 3/ thin films

Abstract

Ferroelectric lead lanthanum titanate (PLT) thin films with compositions varying from pure PbTiO/sub 3/ to PLT 25/100 (0 to 25 mol.% La) were prepared by spin-casting 0.25 M solutions containing metallo-organic precursors of Pb, La and Ti. The as-deposited amorphous films were crystallized into the perovskite structure by heat treatment at temperatures between 450 and 650 degrees C. Dielectric and ferroelectric properties of the thin (410-nm) films were characterized. The dielectric constants of the films varied from approximately 80 to approximately 690 for La contents varying from 0 to 25 mol.%, respectively. Dissipation factors varied from approximately 0.03 to approximately 0.09 over the same compositional range. Also studied was the temperature dependence of the dielectric properties in order to determine the effects of La content on the Curie point (T/sub c/). It is as found that T/sub c/ decreased with increasing La concentration. Coercive field and remanent polarization also decreased with increased La concentration. Hysteresis loops became slim and more symmetric with increasing La content. >