Impact of stress on the crystal structural nonuniformity along the film thickness direction by microfabrication of Pb(Zr,Ti)O₃ islands with morphotropic phase boundary composition

Abstract

Microscopic structure change induced by microfabrication of Pb(Zr,Ti)O₃ (PZT) islands was investigated. The 3 µm-thick epitaxial (100)/(001)-oriented PZT film with Zr/(Zr + Ti) ratio of 0.56 consisted of both tetragonal and the rhombohedral phases. Tetragonal phase mainly existed near the film-substrate interface, while the rhombohedral one near the surface of the film. The profile of this structural non-uniformity along the film thickness was changed by the lateral size of PZT. These phenomena can be explained by the stress distribution in PZT and the understanding of this non-uniformity is the key to control the performance of the devices using PZT.