Raman spectroscopy and X-ray diffraction studies of stress effects in PbTiO3 thin films

A systematic study of domain structure and residual stress evolution with film thickness and of phase transition in c/a epitaxial PbTiO₃/XaAlO₃ films using X-ray diffraction and Raman spectroscopy is reported. Both techniques revealed that the films are under tensile residual stress in the film plane and that a-domains are more stressed than c-domains. The two components of the large A₁(TO) Raman modes are associated with a- and c-domains and their intensity ratio correlates to the volume fraction of o-domains. The evolution of the Raman signature with temperature revealed that the spectrum of a-domains disappears around 480degC, whereas c-domains present an anomaly in their spectrum at 500degC but maintain a well-defined Raman signature up to 600deg C.