Photoconductivity and Local Transport Properties of Single‐Wall Carbon Nanotubes

Photoconducting and local transport properties of single‐wall carbon nanotubes (SWNTs) have been investigated. Two peaks in the photoconductivity excitation spectra around 0.7 and 1.2 eV are observed at room temperature, which can be interpreted as a photocurrent in semiconducting SWNTs. From the local transport measurements on SWNT bundles by the combination of atomic force microscopy and scanning tunneling spectroscopy, we find current flows through each SWNT separately rather than uniformly in the bundle. The results show that we can extract the transport properties of semiconducting or metallic SWNTs from the mixture of both phases by photoconductivity measurements and the local transport measurements.