Photocurrent imaging of semiconducting carbon nanotube devices with local mirrors

摘要

Photocurrent spectroscopy has recently been used by several research groups to study the light-matter interaction in carbon nanotubes. To achieve this, long-channel devices with symmetric metallic contacts are typically used, where photocurrent of opposite sign is generated at the two contacts. However, in short-channel devices (<1 mu m) the diffraction-limited laser spot results in simultaneous excitation of both metal-nanotube contacts and leads to partial cancellation of the photocurrent. In this work, we avoid simultaneous excitation of both metal-nanotube contacts by fabricating an isolated metallic mirror over one of the contacts. With the use of (6,5) carbon nanotubes we demonstrate a unipolar photocurrent signal, that is consistent with the second order interband absorption of a (6,5) nanotube. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim