Condensed Matter Physics Seminar

2 p.m., Thursday, February 26, 2004
Room 1201, Physics Building

 Electrical and Electromechanical Properties of Carbon Nanotube Transistors

Yuval Yaish

(Cornell)

Abstract:  High performance nanotube (NT) transistors are studied using scanned probe techniques. A metallized atomic force microscope (AFM) tip is utilized as a voltage probe to separately measure the contact and intrinsic NT resistances. Our findings show that there is no Schottky barrier between the metal electrode and semiconducting NTs in the hole regime and most of the voltage drop occurs along the NT itself. For metallic NTs we found that there is no current saturation for short tubes, and we have been able to measure the electron-phonon scattering length. In addition, we have used an AFM tip to simultaneously vary the strain in suspended NT and to electrostatically gate the tube. We show that strain can open a bandgap in a metallic NT and modify the bandgap in a semiconducting NT, in agreement with theoretical predictions. We have also studied the effect of axial magnetic field on nanotube band-gap and we have succeeded to lift the subband degeneracy in a controllable way. Finally, by using an electrolyte as a gate, we obtain high performance field-effect transistors from semiconducting single-walled NTs with transconductance as high as 7 S/nm. We will discuss efforts to perform simultaneous electrical and fluorescence detection of biomolecules using NT transistors in a microfluidic channels.
Host:  Fuhrer
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