Epitaxial growth mechanism of Pb(Zr,Ti)O₃ thin films on SrTiO₃ by chemical solution deposition via self-organized seed layer

Abstract

Using scanning transmission electron microscopy and electron energy loss spectroscopy, we have elucidated the local structure and the crystallization mechanism of amorphous phase PbZr_xTi_1−xO₃ (PZT) (x = 0.3) thin films deposited on SrTiO₃ (STO) (001) single-crystal substrates by chemical solution deposition. The amorphous phase involves the short-range order of (Ti/Zr)O₆ octahedra and Pb–O, and then, they are connected with the residual carbon. During the pyrolysis process, the first unit cells of the film has already crystallized with cube-on-cube epitaxial relationship with the STO substrate. The film–substrate interface is coherent and atomically sharp between the first Pb–O layer and the substrate. In the crystallization process, this layer seems to act as a seed layer for PZT epitaxial film growth. It accelerates crystal growth as a nucleation site and simultaneously shrinks the film by combustion of the residual carbon and subsequent densification, affecting the local coordination structure in the amorphous phase. The self-organized seed layer in the pyrolyzed film appears to play an important role in the epitaxial growth.