Date of Award
Doctor of Philosophy (PhD)
Materials Science and Engineering
This project focused on advancing the knowledge of chemical vapour
deposition (CVD) PbTiO₃ thin films for future work on lead zirconate titanate or PZT
(PbZrᵪT₁_ᵪO₃) through an understanding of the structural, chemical and electrical
properties of the material.
A study of the individual oxides, TiO₂ and PbOᵪ, prepared also by CVD, was
made using transmission electron microscopy (TEM), scanning electron microscopy
(SEM), Raman spectroscopy and x-ray diffraction (XRD), before a low pressure, low
temperature process for PbTiO₃ was developed. The major factors in controlling the
film composition and thickness uniformity were identified. The formation sequence
for CVO PbTiO₃ films involved individual oxides of Ti and Pb, rather than
pyrochlore-type phases. A Pb-rich composition ensured the formation of perovskite,
however it resulted in the formation of a thin PbOᵪ surface layer. Removal of this
layer by etching gave improved electrical properties. Capacitance measurements
typically varied less than 1% over the frequency range and gave ε' values from
60-155. At 1 kHz, tan δ was ~0.01 and the resistivity was ~10¹¹Ω.cm.
TEM examination of as-deposited films of PbTiO₃ revealed no macro-domains existed. After post-deposition annealing twinned structures acting as domains were
found in grains, ~0.1 μm in size. The origin of the theoretical minimum grain size
for twinning in PbTiO₃ thin films is discussed. A classification scheme for domain structures was developed based on thin films of PbTiO₃ and PZT. Similarities were
drawn between these domain structures and their bulk counterparts.
The multi-layered bottom electrode of Pt and Ti used in this study was found
to react at temperatures ≤515°C. At higher temperatures (698°C), the Ti layer was
completely consumed, however the top surface of the Pt layer remained unaffected.
Madsen, Lynnette D., "The Properties of Lead Titanate Thin Films produced by Chemical Vapour Deposition" (1994). Open Access Dissertations and Theses. Paper 3952.