Work function of single-walled carbon nanotubes determined by field emission microscopy

The field emission characteristics of a single micro-bundle of single-walled carbon nanotubes (SWCNTs) were investigated using field emission microscopy (FEM). Fowler-Nordheim plots revealed that the work function of the SWCNTs was reduced with increasing heating temperature, and reached a minimum value around 1000 degreesC, assuming that the beta factor was constant during the heating process. Field emission patterns also demonstrated fine structures that were believed to be images of the cap of a SWCNT, which was in a clean state. The radius of the SWCNT micro-bundle was measured by transmission electron microscopy (TEM), and the beta factor was calculated using two empirical formulae. Then, the work function of the SWCNT was determined from the slope, K, of its Fowler-Nordheim plot. The work function values were Phi(1) = 4.76 eV and Phi(2) = 4.88 eV, respectively.Materials Science, MultidisciplinaryPhysics, AppliedSCI(E)EI50ARTICLE4479-4837