Abstract Submitted to the    NANOTUBE'04 Conference:

One of the most attractive properties of single-walled carbon nanotubes (SWNTs) is the electric transport property. Therefore, extensive researches have been reported concerning the application to electronic devices such as field effect transistor (FET). Because pristine SWNTs have been found to behave only as a p-type FET, n-type FET formation method becomes a key factor for further development. Recently, the method such as alkali-metal doping has been developed in order to realize n-type FET. However, usual vapor deposition method used for the alkali-metal intercalation has the inherent problem of air-stability. For this reason, we have carried out an interdisciplinary experimental approach using plasma ion irradiation to create cesium-encapsulated SWNT (Cs@SWNT)[1]. Moreover, we now start to experimentally investigate electric transport of this individual Cs@SWNT.
At first, we made Cs@SWNTs suspension in N,N-dimethylformamide. After then, supersonic treatment was carried out in order to disperse heavily tangled Cs@SWNTs bundles. Sonicated Cs@SWNTs were dripped on a FET substrate. According to the gate-bias (V_G) dependence of current-voltage characteristics between the source-drain electrodes measured at 293 K, we can clearly confirm the V_G dependence that source-drain currents increase with decreasing V_G. In addition, Cs@SWNTs are found to show both the p- and n-type semiconducting properties.

[1] G. –H. Jeong et al., Chem. Commun. (2003) 152; Phys. Rev. B 68 (2003) 075410.