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Published online: 1 October 2008 | doi:10.1038/nchina.2008.231

Nanotubes: Confusing conduction

Tim Reid

Introduction

© (2008) IOP

The performance of carbon nanotubes is strongly affected by structural defects. This has led researchers to propose novel carbon structures, known as haeckelite nanotubes (HNTs), which could have improved electronic properties. Bingrui Li and co-workers at Lanzhou University¹ have performed calculations showing that HNTs could demonstate some unusual conduction phenomena, including 'negative resistance'.

Haeckelite nanotubes are largely composed of Stone–Wales defects, in which the usual hexagon structure switches to pentagons and heptagons (pictured). This type of defect is thought to lower the electronic bandgap of nanotubes, leading to semiconducting or even conducting behaviour.

Li and co-workers simulated the electronic properties of a short segment of HNT suspended either between electrodes made from other HNTs, or between two gold electrodes. Both systems were predicted to have clear metallic (conducting) behaviour. The conduction was not linear, however, and at some points the current was found to decrease with voltage, indicating negative resistance.

The researchers suggest that the negative resistance arose because the conduction energy bands of the electrodes and the sample did not match up. This implies that more unusual transport properties could be discovered in nanoscale carbon electronics, especially when the 'leads' are on the same small scale as the components.

The authors of this work are from:
State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China.

Reference

1. Li, Y. F., Li, B. R. & Zhang, H. L. Ab initio investigations of the transport properties of Haeckelite nanotubes. J. Phys.: Condens. Matter 20, 415207 (2008). | Article |