PHYSICAL PROPERTY OF MOLECULARJ3EVICE CONNECTED WITH INSULATED MOLECULAR WIRES

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We have recently found a novel kind of molecular wire formed by the molecular nanotube synthesized from cyclodextrins (CDs) and a conducting polymer, polyaniline (PANI), and observed the structure of the insulated molecular wire by atomic force microscopy (AFM). This inclusion complex can be regarded as insulated molecular wire, because a conducting polymer is covered by CD molecules as insulator. In this study, we aim to make a molecular device using a single insulated molecular wire as a material for the connection between the external electrodes.For a molecular device connected by the insulated molecular wire, we have successfully made SiO_2 substrates with two electrodes (the gap bewtween electrodes is ca. 500 nm) by AFM lithography. Firstly, we deposited the carbon nanotube to bridge the gap between electrodes on the substrate and measured the resistivity between two electrodes to confirm the quality of the substrate with electrodes. It was found that the resistivity of ca. 100 kΩ measured was dominantly ascribable to the contact resistivity between the electrode and the carbon nanotube. Although we now try to deposit the insulated molecular wire to bridge the gap between electrodes now, the intrinsic conductivity of the molecule is difficult to measure with high accuracy in this system if the resistivity of the insulated molecular wire is smaller than the contact resistivity. Thus, we plan to synthesize PANI with thiol at the both ends to contact well to electrodes.Since it is expected that the doped insulated molecular wire had high conductivity, it can be great candidate of the molecular wire for the molecular device.