Nanoscopic Analysis of Structures and Electric Characteristics of Ferroelectric Molecules by SPM

K. Matsushige, H. Yamada

Department of Electronic Science and Technology, Graduate School of Engineering, Kyoto University, Kyoto, 606-8501 Japan

Scanning probe microscopy (SPM) was utilized to form novel nanometer-scale memory units in organic molecular layers. First, crystal structures and molecular orientation in ferroelectric (VDF/TrFE) films prepared on various substrates were examined, and their temperature variation was also followed. Next, the nanometer-scale polarization switching in the ferroelectric films was achieved by using the SPM technique by applying a positive or a negative electric voltage. The detection of the local ferroeelectric domains were done by monitoring the piezoelectric vibration, revealing that several local domains with different polarities could be formed even within a small crystallite of about 200 nm in length, and thus proving the possibility of the novel and reversible molecular memory. Moreover, surface potential examination was conducted during a heating process, revealing the effect of surface charge and interfacial interaction between the sample and the substrate.