Influence of Misfit Strain on Longitudinal Electro-optic Properties in Preferentially Oriented (Pb,La)(Zr,Ti)O3 Films

Abstract

We successfully fabricated single-crystal-like (Pb,La)(Zr,Ti)O3 (PLZT) films with preferred (100), (110), and (111) orientations on Al-doped ZnO (AZO) coated on (100), (110), and (111) SrTiO3 (ST) substrates. The longitudinal electro-optic (LEO) effect according to crystal orientation was investigated to find the birefringence origin of the LEO effect in oriented PLZT films. The PLZT films with (100) and (111) orientations exhibit promising LEO properties, while in the case of (110)-oriented PLZT films, the LEO effect is very small. From the strain-induced EO effect, this difference in LEO properties in these three kinds of preferentially oriented PLZT films may be attributed to changes in the strain effect from in the PLZT/AZO interfaces. Consequently, we believed that a misfit strain in interfaces between EO films and transparent conductive oxide films is a birefringence origin in oriented films, and control of the misfit strain is a key factor for improving the LEO effect.