JAPAN NANONET BULLETIN - 4th Issue - October 30, 2003

YOUNG RESEARCHERS’ INTRODUCTION

Kenji ISHIDA Lecturer, Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University Researcher, Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Corporation (JST) 1998 Research Assistant, Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University. 2000 Researcher, Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Corporation (JST) 2002 Lecturer, Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University. E-mail address:

Kenji ISHIDA, Lecturer
Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University
Researcher, Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Corporation (JST)

Nanofabrication and functionalization of well-ordered ferroelectric molecules

Molecular electronics have been attracting the interest of many researchers as one of the most important areas in the field of next-generation electronic material. Recently, the research of our group has been focused on the understanding and control of molecular ferroelectricity, which led to the creation of molecular memory. We believe newly synthesized ferroelectric oligomers with low molecular weight may provide a new way to fabricate well-ordered ferroelectric molecular films with large electric dipoles. Using the oligomer molecules in addition to the polymers, we have tried to fabricate well-ordered ferroelectric molecular films and characterize the structural and electrical properties in nanometer scale. An optimum structure with highly efficient ferroelectric performance was studied by total reflection X-ray analysis, infrared spectroscopy and scanning probe microscopy (SPM). A remanent polarization of 130 mC/m²--large among the values reported for organic materials--and poled domain of about 60nm in diameter were realized in VDF oligomer film. The final goal is to clarify the correlation between the nanostructure and ferroelectric behavior at the molecular level.

Fig. 1 Large Image

Schematic diagram of the VDF molecule used in this study. The VDF molecules perform polarization reversal due to the rotation of the electric dipoles,which generated between hydrogen and fluorine atoms in individual molecules.In order to effectively perform the molecular ferroelectricities, it is important to control both the crystal structure and the conformation in the molecules.

Fig. 2 Large Image

Dependence of the poled domain size in the VDF oligomer films on duration time of the pulse voltage. We demonstrate the formation of the local polarized domains in the ferroelectric molecular films by applying electric pulses from a conducting AFM probe used as a positionable top-electrode, and detect their piezoelectricity of the VDF oligomers.