Abstract:
The coexistence of semiconducting and metallic
single-walled carbon nanotubes (SWNTs) during synthesis is one
of the major bottlenecks that prevent their broad application for the
next-generation nanoelectronics. Herein, we present more understanding
and demonstration of the growth of highly enriched
semiconducting SWNTs (s-SWNTs) with a narrow diameter distribution.
An important fact discovered in our experiments is that the
selective elimination of metallic SWNTs (m-SWNTs) from the mixed arrays grown on quartz is diameter-dependent. Our method emphasizes controlling the
diameter distribution of SWNTs in a narrow range where m-SWNTs can be effectively and selectively etched during growth. In order to achieve narrow
diameter distribution, uniform and stable FeW nanoclusters were used as the catalyst precursors. About 90% of as-prepared SWNTs fall into the diameter
range 2.03.2 nm. Electrical measurement results on individual SWNTs confirm that the selectivity of s-SWNTs is ∼95%. The present study provides an
effective strategy for increasing the purity of s-SWNTs via controlling the diameter distribution of SWNTs and adjusting the etchant concentration.
Furthermore, by carefully comparing the chirality distributions of FeW-catalyzed and Fe-catalyzed SWNTs under different water vapor concentrations,
the relationship between the diameter-dependent and electronic-type-dependent etching mechanisms was investigated.
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