Gas molecule effects on field emission properties of single-walled carbon nanotube
Resource
Diamond and Related Materials 13 (4-8): 1306-1313
Journal
Diamond and Related Materials
Journal Issue
13
Pages
1306-1313
Date Issued
2004
Date
2004
Author(s)
Abstract
The effective workfunctions of single-walled carbon nanotubes (5,5) (SWNTs) with various geometries and adsorbates under external electric field have been calculated by the ab initio plane-wave, pseudopotential method. The capped, open-ended, and close-ended nanotubes show the workfunctions of 4.8 eV, 4.43 eV and 3.75 eV, respectively, and these results exhibit a good agreement with experiments. Under external electric field, the effective workfunction is further reduced due to the charge redistribution at the nanotube tip. In addition, the effects of participation of foreign adsorbates on the nanotube surface both physically and chemically on the variations of workfunctions have also been studied. In the physisorption process, the electrostatic interaction between adsorbates and nanotubes plays an important role under external electric field. The polar molecules like water have a large binding energy with the nanotube under electric field. These molecules act as tunneling states for electrons emitting from the nanotube tip into the vacuum. In the chemisorption process, the variations of effective workfunctions can be understood in terms of the surface dipole of the terminated bond due to the different electronegativity between nanotubes and adsorbates. © 2003 Elsevier B.V. All rights reserved.
Subjects
Carbon nanotube; Filed emission; First-principles; Workfunction
Other Subjects
Absorption; Binding energy; Chemisorption; Diamonds; Electric fields; Water; Electrostatic interaction; Gas molecule effects; Carbon nanotubes; diamond
Type
journal article
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