Short channel field-effect transistors from highly enriched semiconducting carbon nanotubes

Semiconducting single-walled carbon nanotubes (s-SWNTs) with a purity of similar to 98% have been obtained by gel filtration of arc-discharge grown SWNTs with diameters in the range 1.2-1.6 nm. Multi-laser Raman spectroscopy confirmed the presence of less than 2% of metallic SWNTs (m-SWNTs) in the s-SWNT enriched sample. Measurement of similar to 50 individual tubes in Pd-contacted devices with channel length 200 nm showed on/off ratios of > 10(4), conductances of 1.38-5.8 mu S, and mobilities in the range 40-150 cm(2)center dot V/s. Short channel multi-tube devices with similar to 100 tubes showed lower on/off ratios due to residual m-SWNTs, although the on-current was greatly increased relative to the devices made from individual tubes.