Alternating current dielectrophoresis of carbon nanotubes

We report on the deposition of individual semiconducting single-walled carbon nanotubes (s-SWNTs) , suspended in an aqueous solution of sodium dodecylsulfate (SDS), onto predefined electrodes using alternating current dielectrophoresis up to 100 MHz. The successful deposition is attributed to the formation of an ionic double layer encapsulating the nanotubes by surface adsorption of the SDS molecules. The nanotube-micella complex formed has a greater polarization than that of the s-SWNTs, which is theoretically shown to be frequency dependent up to 10 GHz. Carbon nanotube field-effect transistors showing large on/off-state current ratios of 108 were demonstrated. (c) 2005 American Institute of Physics.