Tailoring conductivity of carbon nanotubes network by halogen oxoanions

Abstract

Chlorine oxoanions with the chlorine atom at different oxidation states were introduced in an attempt to systematically tailor the electronic structures of single-walled carbon nanotubes (SWCNTs). The degree of selective oxidation was controlled systematically by the different oxidation state of the chlorine oxoanion. Selective suppression of the metallic SWCNTs with a minimal effect on the semiconducting SWCNTs was observed at a high oxidation state. The adsorption behavior and charge transfer at a low oxidation state were in contrast to that observed at a high oxidation state. These results concurred with the experimental observations from X-ray photoelectron spectroscopy. The conversion of metallic SWCNTs to semiconducting ones at high oxidation state might result in an increase in the resistance of the intrinsic SWCNTs but reduces the contact resistance significantly by decreasing the number of metal-semiconductor junctions. The sheet resistance of the SWCNT film decreased significantly at high oxidation states, which was explained in terms of a p-doping phenomenon that is controlled by the oxidation state. © 2009 Materials Research Society.