Characterization of Nanomechanical, Ferroelectric, and Piezoelectric Properties by Nanoindentation and Piezoresponse Force Microscopy of PbTiO3 Thin Films

Lead titanate PbTiO3 films were deposited onto Pt(111)/Ti/SiO2/Si(100) substrates by the aerosol assisted chemical vapor deposition (AA-CVD) process followed by thermal annealing at 550 °C for 12 h. Piezoresponse force microscopic observations revealed a nano laminar domain structure in the PbTiO3 grains, and we attribute the lamellar domains to 180 and 90° ferroelectric domains. The polarization-switching mechanism of the domains in the representative PbTiO3 film under an external electric fields has also been studied, and it was revealed that a large-area polarization switching is usually accompanied by the appearance of a new direction of 90° domains in order to reduce the stress in the grains. Finally, nanomechanical properties such as the elastic modulus and hardness were evaluated by nanoindentation using the continuous stiffness measurement technique.