Development of fabrication method for mono–polycrystalline Pb(Zr, Ti)O₃ composite thin film using selective wet etching of epitaxial buffer layer

This paper reports on a simple method to fabricate Pb(Zr,Ti)O₃ (PZT) thin films with a composite structure, where monocrystalline (mono) PZT is segmented by elongated polycrystalline (poly) mesh patterns. The motivation of this study is to overcome the inherent mechanical brittleness of piezoelectric mono thin films by adding a poly PZT pattern to the mono thin film. First, an SrRuO3 epitaxial buffer layer for the PZT was modified into a mesh pattern by wet etching. PZT was then sputter-deposited onto it. The analytical results of the deposited thin film showed that this method can be used to fabricate mono–poly composite thin films. This achievement leads to the ease of fabricating piezoelectric thin films with a third crystal structure, which is neither poly nor mono, and has the potential to create a new thin film with moderate properties that are a balance between those of mono and poly thin films.