Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 15: Devices

HL 15.4: Talk

Monday, February 25, 2008, 12:00–12:15, ER 164

Carbon Nanotube Field-Effect Transistors Probed by — •Eduardo Lee, Kannan Balasubramanian, Marko Burghard, and Klaus Kern — Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569, Stuttgart

Carbon nanotube field-effect transistors (CNFETs) have attracted substantial interest due to their potential use in (opto)-electronics. For instance, CNFETs have been shown to display photoconductivity, thus being interesting for light detecting devices. On the other hand, despite the rapid development on the understanding and performance of CNFETs, several issues are still to be investigated in more detail, such as the carbon nanotube (CNT)-metal interfaces, and the spatial origin of their photoconductive response. Scanning photocurrent microscopy (SPCM) has been shown to be a potentially powerful tool to characterize CNFETs. Strong photocurrent responses are typically observed at the contacts, resulting from the Schottky barriers. Moreover, the ability to spatially resolve the photocurrent responses, enables the investigation of CNT photoconductivity in more detail.

This contribution reports on SPCM characterization of field-effect transistors based on CNTs. Photocurrent images are obtained for zero and non-zero drain-source biases. It is demonstrated that the close relationship between the photocurrent response and the local electric field, enables the mapping of the electrostatic potential profile through SPCM characterization. Finally, it is shown that the photoconductive response does not occur homogeneously within the device.