Imaging of Carbon Nanotube Electronic States Polarized by the Field of an Excited Quantum Dot

Duc Nguyen, Alison Wallum, Huy A. Nguyen, Nhan T. Nguyen, Joseph W. Lyding, Martin Gruebele

Research output: Contribution to journalArticlepeer-review


Efficient heat dissipation and large gate capacitance have made carbon nanotube field-effect transistors (CNT FETs) devices of interest for over 20 years. The mechanism of CNT FETs involves localization of the electronic structure due to a transverse electric field, yet little is known about the localization effect, nor has the electronic polarization been visualized directly. Here, we co-deposit PbS quantum dots (QDs) with CNTs and optically excite the QD so its excited-state dipolar field biases the local environment of a CNT. Using single-molecule absorption scanning tunneling microscopy, we show that the electronic states of the CNT become transversely localized. By nudging QDs to different distances from the CNT, the magnitude of the localization can be controlled. Different bias voltages probe the degree of localization in different CNT excited states. A simple tight-binding model for the CNT in an electrostatic field provides a semiquantitative model for the observed behavior.

Original languageEnglish (US)
Pages (from-to)1012-1018
Number of pages7
JournalACS Nano
Issue number2
StatePublished - Feb 26 2019


  • Carbon nanotube
  • Dipole-induced polarization
  • Quantum dot
  • Single-molecule absorption scanning tunneling microscopy
  • Tight-binding calculation

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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