Combined transport and Raman measurements on individual carbon nanotubes

Combined techniques for measurement of structural, transport, and spectroscopic properties of individual carbon nanotubes are very important for current progress in the physics of these materials. We have measured the Raman spectra of individual single walled nanotubes that are electrically contacted with lithographically fabricated microelectrodes on Si/SiO substrates. The G-band of the Raman spectra have characteristic features for metallic and semiconducting tubes that we are able to discern. This conclusion is confirmed by transport measurements that unambiguously distinguish between the two types of tubes.