Electron tunneling in carbon nanotube

Electron tunneling in carbon nanotube composites

C Gau, Cheng-Yung Kuo and H S Ko
Institute of Aeronautics and Astronautics, and Center for Micro/Nano Science and

Technology, National Cheng Kung University, Tainan, Taiwan

E-mail: gauc@mail.ncku.edu.tw

Received 2 July 2009

Published 2 September 2009


Abstract

Nanocomposites, such as polymer blending with carbon nanotubes (CNTs), have been shown to

have a drastic reduction in the resistivity and become conductive when the CNTs concentration

has reached a certain percolation threshold. The reduction could be more than a millionth of the

original polymer material. This has been realized as the formation of an infinite cluster of

connected CNTs or pathways. Therefore, the conductivity of a nanocomposite should follow

that of CNTs. Here we show that the resistivity of a nanocomposite is not governed by the

interconnected CNTs, but the polymer between neighboring CNTs. That is, polymer–CNTs

exhibit the nature of a conducting polymer, which can be explained as the tunneling of electrons

one by one from the first CNT electrode to the next-nearest CNT electrode, forming a

CNT/polymer pathway. A conduction model based on the tunneling of electrons passing, one

by one, through the polymer gap between two neighboring CNT electrodes is formulated and

derived. This model can accurately predict the significant reduction of the polymer–CNTs’

resistivity with the addition of CNTs. The temperature effect can be readily incorporated to

account for resistivity variation with the temperature of this nanocomposites.