PREPARATION AND PROPERTIES OF (PB,LA)(ZR,TI)O3 THIN-FILMS BY METALORGANIC CHEMICAL VAPOR-DEPOSITION

Lanthanum-modified lead zirconate titanate (PLZT) thin films have been grown on Pt/MgO(100) and Pt/SiO2/Si substrates at 650-degrees-C by metalorganic chemical vapor deposition using Pb(C2H5)4, La(DPM)3, Zr(DPM)4 and Ti(i - OC3H7)4 as the source materials. The properties of PLZT films were investigated as a function of the La content in a range of 0-15 at.% with a composition ratio of Zr/(Zr + Ti) < 0.5. The films were of a single perovskite structure, and highly oriented to the c axis of the tetragonal phase on a Pt/MgO(100) substrate. The films were transformed from tetragonal to nearly cubic as the La content was increased. The films were colorless and transparent, and the surface morphology became smoother through an La addition. The relative dielectric constants increased as the La content was increased up to about 5 at.%. The remanent polarizations were 25-30-mu-C/cm2, and the coercive field decreased from 53 to 30 kV/cm as the La content was increased in the films having Zr/Ti = 40/60.