Controlled synthesis and enhanced field emission characteristics of conical carbon nanotubular arrays |
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| Authors: | Santoshrupa Dumpala Abdelilah Safir David Mudd Robert W Cohn Mahendra K Sunkara Gamini U Sumanasekera |
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| Affiliation: | aDepartment of Chemical Engineering, University of Louisville, Louisville, KY 40292, USA;bThe Electro-Optics Research Institute and Nanotechnology Center, University of Louisville, Louisville, KY 40292, USA;cDepartment of Physics, University of Louisville, Louisville, KY 40292, USA |
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| Abstract: | Conical carbon nanotubes (CCNTs) with unique structural characteristics arising from their tapered morphologies compared to uniform diameter carbon nanotubes, have been shown to exhibit enhanced field emission properties and support high current densities. Specifically, several CCNT arrays with different morphological characteristics (tip radius, aspect ratio, density and wall structure) were synthesized by variations in the process parameters using a microwave plasma chemical vapor deposition (MWCVD) reactor. The field emission characteristics for a CCNT array sample with a tip radius of 5 nm, density of 108/cm2 and having the highest aspect ratio exhibited a low turn-on electric field (< 0.7 V/μm) and a high field enhancement factor (β > 7500). Other samples with lower emission characteristics were attributed either to the presence of field screening effect resulting from higher CCNT density or due to the corresponding tip and wall characteristics. |
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