Laser-induced nanoscale thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes.
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Although aligned arrays of single-walled carbon nanotubes (SWNTs) have outstanding potential for use in broad classes of advanced semiconductor devices, the relatively large population of metallic SWNTs (m-SWNTs) that results from conventional growth techniques leads to significantly degraded performance. Recently reported methods based on thermocapillary effects that enable removal of m-SWNTs from such arrays offer exceptional levels of efficiency, but the procedures are cumbersome and require multiple processing steps. Here we present a simple, robust alternative that yields pristine arrays of purely semiconducting SWNTs (s-SWNTs) by use of irradiation with an infrared laser. Selective absorption by m-SWNTs coated with a thin organic film initiates nanoscale thermocapillary flows that lead to exposure only of the m-SWNTs. Reactive ion etching eliminates the m-SWNTs without damaging the s-SWNTs; removal of the film completes the purification. Systematic experimental studies and computational modeling of the thermal physics illuminates the essential aspects of this process. Demonstrations include use of arrays of s-SWNTs formed in this manner as semiconducting channel materials in statistically relevant numbers of transistors to achieve both high mobilities (>900 cm2 V(-1) s(-1)) and switching ratios (>10(4)). Statistical analysis indicates that the arrays contain at least 99.8% s-SWNTs and likely significantly higher.
author list (cited authors)
Du, F., Felts, J. R., Xie, X. u., Song, J., Li, Y., Rosenberger, M. R., ... Rogers, J. A.
complete list of authors
Du, Frank||Felts, Jonathan R||Xie, Xu||Song, Jizhou||Li, Yuhang||Rosenberger, Matthew R||Islam, Ahmad E||Jin, Sun Hun||Dunham, Simon N||Zhang, Chenxi||Wilson, William L||Huang, Yonggang||King, William P||Rogers, John A