title: Dose-controlled, floating evaporative self-assembly and alignment of semiconducting carbon nanotubes from organic solvents.
abstract: Arrays of aligned semiconducting single-walled carbon nanotubes (s-SWCNTs) with exceptional electronic-type purity were deposited at high deposition velocity of 5 mm min(-1) by a novel "dose-controlled, floating evaporative self-assembly" process with excellent control over the placement of stripes and quantity of s-SWCNTs deposited. This approach uses the diffusion of organic solvent on the water-air interface to deposit aligned s-SWCNT (99.9%) tubes on a partially submerged hydrophobic substrate, which is withdrawn vertically from the surface of water. By decoupling the s-SWCNT stripe formation from the evaporation of the bulk solution and by iteratively applying the s-SWCNTs in controlled "doses", we show through polarized Raman studies that the s-SWCNTs are aligned within ±14°, are packed at a density of ∼50 s-SWCNTs μm(-1), and constitute primarily a well-ordered monodispersed layer. The resulting field-effect transistor devices show high performance with a mobility of 38 cm(2) V(-1) s(-1) and on/off ratio of 2.2 × 10(6) at 9 μm channel length.
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin , Madison, Wisconsin 53706, United States.
authors.forename: Yongho
authors.initials: Y
authors.lastname: Joo
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Brady
authors.forename: Michael S
authors.initials: MS
authors.lastname: Arnold
authors.forename: Padma
authors.initials: P
authors.lastname: Gopalan