We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, lay...We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, layer positions, and optical absorbance spectra of SWNT separations using the bile salt sodium deoxycholate （DOC） and the anionic salt sodium dodecyl sulfate （SDS）, we clarify the roles and interactions of these two surfactants in yielding different DGU outcomes. The separation mechanism described here can also help in designing new DGU experiments by qualitatively predicting outcomes of different starting recipes, improving the efficacy of DGU and simplifying post-DGU fractionation.展开更多
Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as t...Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as the back-gate electrode. Fabrication consisted of patterned catalyst deposition by surface modification followed by dip-coating and synthesis of SWNTs by alcohol chemical vapor deposition （CVD）. The electrodes and channel were grown simultaneously in one CVD process. The resulting FETs exhibited excellent performance, with an I ON/I OFF ratio of 10^6 and a maximum ON-state current （/ON） exceeding 13 uA. The large I ON is attributed to SWNT bundles connecting the SWNT channel with the SWNT electrodes. Bundling creates a large contact area, which results in a small contact resistance despite the presence of Schottky barriers at metallic-semiconducting interfaces. The approach described here demonstrates a significant step toward the realization of metal-free electronics.展开更多
基金Acknowledgements Part of this work was financially supported by Grant- in-Aid for Scientific Research （No. 22226006 and 19054003）, ＂Development of Nanoelectronic Device Technology＂ of New Energy and Industrial Technology Development Organization （NEDO）, and the Global Centers of Excellence （COE） Program ＂Global Center for Excellence for Mechanical Systems Innovation＂. P. Z. acknowledges a scholarship granted by the China Scholarship Council and G. L. acknowledges support from the NanoJapan program funded by the National Science Foundation.
文摘We present a systematic study of the effects of surfactants in the separation of single-walled carbon nanotubes （SWNTs） by density gradient ultracentrifugation （DGU）. Through analysis of the buoyant densities, layer positions, and optical absorbance spectra of SWNT separations using the bile salt sodium deoxycholate （DOC） and the anionic salt sodium dodecyl sulfate （SDS）, we clarify the roles and interactions of these two surfactants in yielding different DGU outcomes. The separation mechanism described here can also help in designing new DGU experiments by qualitatively predicting outcomes of different starting recipes, improving the efficacy of DGU and simplifying post-DGU fractionation.
文摘Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as the back-gate electrode. Fabrication consisted of patterned catalyst deposition by surface modification followed by dip-coating and synthesis of SWNTs by alcohol chemical vapor deposition （CVD）. The electrodes and channel were grown simultaneously in one CVD process. The resulting FETs exhibited excellent performance, with an I ON/I OFF ratio of 10^6 and a maximum ON-state current （/ON） exceeding 13 uA. The large I ON is attributed to SWNT bundles connecting the SWNT channel with the SWNT electrodes. Bundling creates a large contact area, which results in a small contact resistance despite the presence of Schottky barriers at metallic-semiconducting interfaces. The approach described here demonstrates a significant step toward the realization of metal-free electronics.
