Composition Dependency of Epitaxial Pb(Zr,Ti)O_3 Films with Different Film Thickness

摘要

Epitaxial Pb(Zr_xT_(1-x))O_3 films with 200 nm and 2 mu m thickness were grown by metal organic chemical vapor deposition. Crystal symmetry changed from tetragonal to rhom-bohedral with increasing x value in Pb(Zr_xTi_(1-x))O_3 [x = Zr/(Zr+Ti)] for both film thickness and a region for the co-existence of the mixture of tetragonal and rhombohedral exists around x = 0.5, becoming a little wider with increasing film thickness. Saturation and remanent polarizations (P_(sat) and P_r) showed a minimum near x = 0.5 irrespective of the film thickness. The P_r/P_(sat)t ratio also showed a minimum in case of 200 nm thick films, but such a minimum in P_r/P_(sat) was not observed in case of 2 mu m thickness. Relative dielectric constant showed a maximum near x = 0.5 for both film thickness, but the effective longitudinal piezoelectric constant did not show any noticeable maximum near x = 0.5 irrespective of the film thickness, differently from the reported data for the sintered body.