title: Importance of diameter control on selective synthesis of semiconducting single-walled carbon nanotubes.
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 Fe-W nanoclusters were used as the catalyst precursors. About 90% of as-prepared SWNTs fall into the diameter range 2.0-3.2 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 Fe-W-catalyzed and Fe-catalyzed SWNTs under different water vapor concentrations, the relationship between the diameter-dependent and electronic-type-dependent etching mechanisms was investigated.
authors.affiliation: Department of Chemistry and ‡Department of Physics, Duke University , Durham, North Carolina 27708, United States .
authors.forename: Jinghua
authors.initials: J
authors.lastname: Li
authors.forename: Chung-Ting
authors.initials: CT
authors.lastname: Ke
authors.forename: Kaihui
authors.initials: K
authors.lastname: Liu
authors.forename: Pan
authors.initials: P
authors.lastname: Li
authors.forename: Sihang
authors.initials: S
authors.lastname: Liang
authors.forename: Gleb
authors.initials: G
authors.lastname: Finkelstein
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu