Domain formation in lead titanate ferroelectric thin films

Epitaxial lead titanate ferroelectric thin films were grown on strontium titanate(001) and dysprosium scandate(110) substrates by RHEED controlled pulsed laser deposition. We used high resolution transmission electron microscope to investigate the structure of the films. The clear difference in the shape of the a-domains were observed in films on the two different substrates. Films on strontium titanate substrates were found to have wedge shaped a-domains whereas, a-domains in the films on the dysprosium scandate substrates were found to have nearly uniform width. The difference in the shape of a-domains is attributed to the difference in stiffness of the two substrates. Nanoindentations on the substrates were performed to quantify their the stiffness. In another set of experiment we have successfully grown completely c-oriented lead titanate thin films with various thicknesses ranging from 22–340 nm on strontium titanate substrates. Laser pulse frequency (growth rate) is the crtical parameter for the formation of a-domain free lead titanate films. The strontium titanate substrate surface termination is also important at higher growth rates.