Piezoresponse Images Research Articles

Investigation of Surface Potential of Ferroelectric Organic Molecules by Scanning Probe Microscopy

The surface potential of ferroelectric copolymer films of vinylidene fluoride and trifluoroethylene was investigated by scanning probe microscopy. The results reveal that the as-deposited copolymer films on a graphite substrate show a negative surface potential. The surface potential is ascribed to the substrate-induced effect, which causes frozen dipoles in the copolymer films. We made locally poled areas in the films using a conductive cantilever tip and measured the piezoelectric response of the films with a modified scanning force microscope. The observed asymmetric behavior of the piezoelectric response of the thin films can be consistently explained by the frozen ferroelectric layer in the films. Both surface potential and piezoresponse images of locally polarized areas were also obtained. The results indicate that the charge transferred from the tip overcompensated for the oriented dipoles and that the surface potential of the poled regions was attributed to the excess charge.

Characterization of Ferroelectric BaTiO3 (100) Surfaces by Variable Temperature Scanning Surface Potential Microscopy and Piezoresponse Imaging

AbstractVariable temperature atomic force microscopy (AFM), scanning surface potential microscopy (SSPM) and piezoresponse imaging were applied to the characterization of a model BaTiO3(100) surface. The influence of the domain structure on surface topography, surface potential and piezoresponse image is discussed. The domain induced surface corrugations and piezoelectric response were found to disappear above the Curie temperature in full agreement with theoretical expectations. Relaxation of apparent surface potential after the transition to paraelectric state on heating and during the transition to ferroelectric state on cooling was observed. The kinetics of potential relaxation was orders of magnitude slower than that of the transition.

Scanning force microscopy study of domain structure in pb (zrxti1-x)o3 thin films and pt/pzt/pt and ruo2/pzt/ruo2 capacitors

A piezoresponse technique based on scanning force microscopy has been used for studying domain structure in ferroelectric thin films. Studies were performed on Pb(Zrx,Ti1-x)O3 (PZT) thin films and PZT-based capacitors with the ferroelectric layer produced by a sol-gel method. Piezoresponse images were taken for different systems materials: (a) before and after inducing polarization in PZT films by applying a dc voltage between the bottom electrode and the SFM tip, and (b) on top electrodes of fatigued and non-fatigued Pt/PZT/Pt and RuO2/PZT/RuO2 capacitors. Effect of the PZT film and capacitor structures on the imaging resolution of domains is discussed.

Scanning force microscopy for the study of domain structure in ferroelectric thin films

A piezoresponse technique based on scanning force microscopy (SFM) has been used for studying domain structure in ferroelectric thin films. Studies were performed on Pb(Zrx,Ti1−x)O3(PZT) thin films produced by a sol–gel method. The piezoresponse images of the PZT films were taken before and after inducing polarization in the films by applying a direct current voltage between the bottom electrode and the SFM tip. Polarization induced patterns were written with 20 V pulses and subsequently imaged by the SFM piezoresponse technique. The effect of the film structure on the imaging resolution of domains is discussed.