Kaori Matsuura

Scanning nonlinear dielectric microscopy with nanometer resolution

A very high-resolution scanning nonlinear dielectric microscope was developed for the observation of ferroelectric polarization. We demonstrate that the resolution of the microscope is of a nanometer order by measurement of the c–c domain wall of a BaTiO3 single crystal, and that this microscope is very useful not only for the domain observation of ferroelectric bulk material but also for that of thin films.

Measurement of the Ferroelectric Domain Distributions Using Nonlinear Dielectric Response and Piezoelectric Response

Scanning nonlinear dielectric microscopy (SNDM) is the first successful purely electrical method for observing the ferroelectric domain distributions. At present its resolution is of the sub-nanometer order. As another method for measuring the ferroelectric domains, the piezoelectric response imaging method is often used. In this study, we compare the resolution of SNDM with that of piezoelectric response imaging and confirm that SNDM gives a much higher resolution than that obtained by piezoelectric imaging. A fundamental study to apply the SNDM system to the ferroelectric reading and writing system is also performed.

Scanning Nonlinear Dielectric Microscopy with Contact Sensing Mechanism for Observation of Nanometer Sized Ferroelectric Domains

A new scanning nonlinear dielectric microscope with very high resolution for the observation of ferroelectric polarization was developed. This microscope has a newly developed contact sensing mechanism for detecting the exact contact point of a probe needle with respect to the surface of a specimen. This contact sensing mechanism enables us to use a probe needle with a very thin pointed end. Using the new microscope, domains in BaTiO3 single crystal and in PbTiO3 thin film were observed. By measuring the c-c domain wall of BaTiO3, the microscope was confirmed to have nanometer-order resolution.

Observation of domain walls in PbZr0.2Ti0.8O3 thin film using scanning nonlinear dielectric microscopy

Using scanning nonlinear dielectric microscopy (SNDM), we measured the linear dielectric constant of a domains (c axis in the plane of the film) and c domains (c axis perpendicular to the film surface) in PbZr0.2Ti0.8O3 (PZT) thin film to confirm that the dielectric constant of the a domain is higher than that of the c domain. We observed 90° a–c domain walls and 180° c–c domain walls and found that, experimentally, the 180° c–c domain wall was smaller than the 90° a–c domain wall.

Fundamental Study on Nano Domain Engineering Using Scanning Nonlinear Dielectric Microscopy

Scanning nonlinear dielectric microscopy (SNDM) is the first successful purely electrical method for observing the ferroelectric domain on the sub-nanometer order. As another high-resolution method for measuring ferroelectric domains, the piezoelectric response imaging method is often reported. In this study, it is confirmed that SNDM has a much higher resolution than piezoelectric imaging under the same experimental condition using the same system. First, the resolution of SNDM is described, and then, the resolution of SNDM is compared with that of piezoelectric imaging. Finally, a fundamental study for applying the SNDM system to a ferroelectric reading-recording system is performed, and it is concluded that SNDM has sufficient performance for application to the ferroelectric memory system.

Observation of Ultrathin Single-Domain Layers Formed on LiTaO3 and LiNbO3 Surfaces Using Scanning Nonlinear Dielectric Microscope with Submicron Resolution

The formation of very thin domain layers on the surface of multidomain lithium tantalate by heat treatment is observed by scanning nonlinear dielectric microscopy. A similar phenomenon of forming a very thin single-domain layer was also observed on the surface of periodically polarized lithium niobate single crystal. By measuring the thickness of the single-domain layers, the depth sensitivity of the scanning nonlinear dielectric microscope with submicron resolution was estimated.

Characterization of Ferroelectric Property of C-Axis- and Non-C-Axis-Oriented Epitaxially Grown Bi2VO5.5 Thin Films

Epitaxial Bi2VO5.5 films with c-axis- and non-c-axis-orientations were grown by metalorganic chemical vapor deposition. (001)-, (114)- and (102)-oriented Bi2VO5.5 films were epitaxialy grown on (100), (110) and (111)SrTiO3 substrates, respectively. Electrical properties of the (001)- and (114)-oriented films on (100)SrRuO3∥(100)SrTiO3 and (110)SrRuO3∥(110)SrTiO3 substrates were compared. The dielectric constant (er) of the (001)-oriented film was smaller than that of the (114)-oriented one, suggesting that er along the c-axis is smaller than that along other axes. Leakage current density of the (001)-oriented film was smaller than that of the (114)-oriented one. These results were in good agreement with those of the crystallographically equivalent oriented films of SrBi2Ta2O9 and Bi4Ti3O12. Ferroelectricity and domain structure were observed for both films by Polarization-Electric field measurements and scanning nonlinear dielectric microscopy, respectively. However, the large difference of remanent polarization depending on the film orientation observed for SrBi2Ta2O9 and Bi4Ti3O12 films was not observed for Bi2VO5.5 films.

Scanning Nonlinear Dielectric Microscope with Submicron Resolution.

A new probe using a tungsten needle for the scanning nonlinear dielectric microscope has been developed. This probe has a submicron resolution. This probe combined with a submicron stage is used to observe the distribution of domains in a lithium tantalate substrate with a proton exchanged inversion layer and also in polarized and depolarized lead zirconate titanate ceramics.

Nano domain engineering using scanning nonlinear dielectric microscopy

Scanning nonlinear dielectric microscopy (SNDM) is the first successful purely electrical method for observing ferroelectric domains. Its resolution has now reached the sub-nanometer order. In this paper, a fundamental study on application of the SNDM system to a ferroelectric reading and writing system is performed. First, to check the performance of the SNDM system as a ferroelectric recording system, we conduct a fundamental study on the writing of a domain inversion dot in a PZT thin film and succeed in achieving very small domain dots with a size of 25 nm. Next, we form small inverted domain dots in stoichiometric LiTaO/sub 3/ single crystals for the purpose of a basic investigation of domain dynamics in a very small area. The relationship between the voltage for domain reversal and the inverted area and the relationship between the inverted domain area and the voltage application time are obtained.

Observation of artificial nano-domains in ferroelectric thin films using nonlinear dielectric imaging and piezo imaging

Abstract We have developed scanning nonlinear dielectric microscopy (SNDM) that is the first successful purely electrical method for observing polarization distributions of ferroelectric materials. Now the resolution of SNDM has been improved to sub-nanometer. On the other hand, the piezoelectric response imaging (piezo-imaging) using scanning force microscopy (SFM) is well known as the method for observing the polarization distributions. In this study, we compare the resolution of SNDM with that of the piezo-imaging and confirm that the resolution of SNDM is much higher than that of piezo-imaging. Then, as the fundamental study to apply the SNDM system to a ferroelectric reading-recording system, we switched and observed the ferroelectric domains using the SNDM system.