Investigation of nonswitching regions in ferroelectric thin films using scanning force microscopy

Nonswitching regions which degrade the electrical properties of ferroelectric thin films were investigated by scanning probe microscopy. An 80-nm-thick PbZr0.5Ti0.5O3(001)(PZT) ferroelectric thin film and a YBa2Cu3O7-δ (100) bottom electrode were grown on SrTiO3(100) substrates by the pulsed laser deposition method. We successfully detected nonswitching regions in the PZT thin films by measuring ferroelectric hysteresis loops using a scanning probe microscope, and the hysteresis loops showed an asymmetric shift toward negative remanent polarization. It is suggested that the nonswitching regions originate from dislocations caused by a lattice mismatch between the PbZr0.5Ti0.5O3(001) and the YBa2Cu3O7-δ(100). The effective thickness of the nonswitching regions is estimated to be 20 nm from the amount of the shift of the hysteresis loops.