Scanning field emission from patterned carbon nanotube films

Abstract

The investigation of the field emission (FE) properties of carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals a strong dependence on the density and morphology of the CNT deposit. Large differences between the microscopic and macroscopic current and emission site densities are observed, and explained in terms of a variation of the field enhancement factor β. As a consequence, the emitted current density can be optimized by tuning the density of CNTs. Films with medium densities (on the order of 107 emitters/cm2, according to electrostatic calculations) show the highest emitted current densities.

Efficient field emission from structured gold nanowire cathodes

“…These results reflect the complex interplay of the shape, number density and cluster formation of NW on the FE homogeneity and current carrying capability of Au-NW patches. The mutual shielding effects within the NW patches have a strong influence on their field enhancement as well known for densely grown CNT [18].…”

Formation and characterization of carbon nanowires

“…19 Lower values of applied field, corresponding to higher enhancement factors, are sometimes reported from ideal aligned nanowires and nanotubes. 12,19 However, at high areal densities inter nanowire proximity screening becomes a significant factor. In a similar work by Nilsson et al, 12 they estimated that the ideal average separation between nanowires should be about twice the length of nanowire.…”

Carbon based electronic materials: applications in electron field emission

“…When the density of nanotubes is high screening of the applied field occurs which results in poor emission efficiency. Experimental evidence for the effects of field screening have been reported by Nilsson et al [27] in mats of nanotubes.…”