Effect of the residual stress induced by external stress application on dielectric properties of epitaxial lead titanate film

Relationships among in-plane residual stress and some dielectric properties (remanent polarization, coercive field, dielectric permittivity, etc.) wer e investigated on ferroelectric thin films. Epitaxial PbTiO3 thin films wer e deposited on Pt/(100) SrTiO3 substrate by MOCVD. Residual stresses of the films were determined by a modified sin(2)psi method. The external stress in this study could be varied from +2.0 GPa up to +6.0 GPa. We first observ ed the change of the dielectric properties together with the tensile stress application in actual experiments; decrease of the remanent polarization f rom 11 mu C.cm(-2) down to 3 mu C.cm(-2) and of the coercive field from 115 kV.cm(-1) down to 95 kV.cm(-1). The Curie temperature of the him was decre ased from 450 degrees C to 437 degrees C with increasing the residual stres s, while the dielectric permittivity at room temperature was measured to be approximately 210, irrespectively of the residual stress. Further, the ten sile stress caused deformation of PbTiO3 crystal lattice, which was describ ed as the decrease of the cia ratio. We conclude that the residual stress v aried the dielectric properties by deforming the crystal lattice.