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HL: Halbleiterphysik

HL 9: Poster I

HL 9.82: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Photoelectronic Transport Imaging (PETI) of Individual Carbon Nanotubes — •Eduardo Lee, Kannan Balasubramanian, Marko Burghard, and Klaus Kern — Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart, 70569

Carbon nanotubes (CNTs) display a range of interesting properties, which make them attractive as components of nanoscale electronic devices. However, the operation mechanism of CNT-based devices is still not thoroughly understood. To overcome this limitation, local probe techniques have proven as highly valuable tools. Photoelectronic transport imaging (PETI) is one such methods which involves the acquisition of photo-generated current images while scanning the sample through a diffraction-limited laser spot. The resulting PET images contain signatures of local charge transport barriers that may arise from charge transfer at the interface to attached electrodes or defects along the nanotubes such as intramolecular junctions. In fact, previous PETI studies of both semiconducting and metallic single-wall carbon nanotubes (SWCNTs) revealed strong photocurrent responses at the contacts due to the local Schottky-like barriers. In the present contribution, gate voltage-dependent PETI is applied to investigate these contact barriers in more detail. For the semiconducting tubes, it was observed that the photocurrent signal at the contacts is suppressed upon band flattening through the applied gate potential. This behavior is distinguished from the metallic tubes, for which no significant changes could be detected upon gate potential variation.