Structural characterisation of sol-gel PZT thin films

The techniques of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission and scanning transmission electron microscopy (TEM/STEM) have been applied to the analysis of thin films of Pb(Zr_0.30Ti_0.70)O₃ (PZT30/70) deposited at low-temperatures (510°C) by a sol-gel process onto Pt/Ti electrodes on SiO₂/Si 100 substrates. It is found that the platinum film is highly oriented with the 111 axis perpendicular to the substrate plane. The ferroelectric film tends to crystallise epitaxially upon this as columnar crystals. There are indications of the existence of a second metallic phase at the interface between the platinum and the PZT30/70 film which may be associated with its nucleation. The TEM shows the boundaries between individual sol-gel layers, although the growing crystallites of the PZT30/70 propagate through these boundaries unhindered. The XPS and Auger analysis have shown that Pb penetrates through the Pt layer to the underlying Ti layer, even at the low crystallisation temperatures used. There is also clear evidence for diffusion of the Zr and Ti prior to, or during the crystallisation process, so that the Zr migrates to the surface of each sol-gel layer