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Role of single defects in electronic transport through carbon nanotube field-effect transistors
Marcus Freitag1, A T Johnson, Sergei V Kalinin
1Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
Abstract:
The influence of defects on electron transport in single-wall carbon nanotube field-effect transistors (CNFETs) is probed by combined scanning gate microscopy (SGM) and scanning impedance microscopy (SIM). SGM images are used to quantify the depletion surface potential, and from this the Fermi level, at individual defects along the CNFET length. SIM is used to measure the voltage distribution along the CNFET. When the CNFET is in the conducting state, SIM reveals a uniform potential drop along its length, consistent with diffusive transport. In contrast, when the CNFET is "off," potential steps develop at the position of depleted defects. High-resolution imaging of a second set of weak defects is achieved in a new "tip-gated" SIM mode.