Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.20: Poster

Dienstag, 26. Februar 2008, 16:30–19:00, Poster D

Suspended carbon nanotube quantum dots — •Andreas K. Hüttel and Herre van der Zant — Molecular Electronics and Devices, Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands

The vibrational modes of single suspended carbon nanotubes (CNT’s) are studied in low temperature transport measurements. The low-energy single electron tunneling excitation spectrum of the quantum dots embedded in a suspended single wall CNT displays harmonic excited states at an energy scale compatible to the longitudinal (stretching) mechanical mode. Agreement with Franck-Condon theory has been observed.

Our work targets this interplay of electrical and mechanical effects, also towards resolving the transversal (bending) mechanical mode of the nanotube in electronic transport. Several approaches in terms of sample geometry and fabrication technique are presented, e.g. using very short nanotube segments as single quantum dots to enhance level spacing, or using double quantum dots to enhance spectroscopic resolution. Measurements indicate for a certain nanotube suspension length range a current suppression at low bias, consistent with “phonon” or “distortion” blockade mechanisms due to the transversal vibration mode. Further data will be presented.