Electrical transport characteristics of surface-conductance-controlled, dielectrophoretically separated single-walled carbon nanotubes.

Alternating current dielectrophoresis has attracted considerable attention as a possible candidate to separate single-walled carbon nanotubes according to electronic types. Recently, the significant effect of surface charge on the polarizability of semiconducting nanotubes was demonstrated using comparative Raman spectroscopic studies. Here we present electrical transport characteristics of surface-charge-controlled, dielectrophoretically deposited nanotube arrays. The surface charge was controlled using cationic/anionic surfactant mixtures. Complete separation between metallic and semiconducting species was achieved at the electric field frequency of 10 MHz only when the surface charge of nanotubes was neutralized, which is consistent with previous Raman investigation. A theoretical analysis, using zeta potential information as input, further supported the experimental observation.