Effect of Cathode–Anode Distance on Field Emission Properties for Carbon Nanotube Film Emitters

概要

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The influence of the cathode–anode distance (gap) on field emission (FE) properties is investigated for carbon nanotube film emitters. Any increase in the gap can cause a clear shift in the plot of emission current ($I$) against applied field ($E_{\text{A}}$) ($I$–$E_{\text{A}}$ curve) to the low field regime, resulting from an increase in the corresponding field enhancement factor ($\beta_{\text{FN}}$). However, normalization of these $I$–$E_{\text{A}}$ curves through the use of the local field ($E_{\text{L}}$) concept shows that the emission sites are invariant during a change in the gap, although they attain stronger $E_{\text{L}}$ at larger gaps. When a modified Fowler–Nordheim plot [$\ln(I/E_{\text{A}}^{2})$–$2\ln\beta_{\text{FN}}$ vs $1/E_{\text{A}}$] is employed, the plots obtained at various gaps provide a unique intercept with the vertical axis, consistent with the experimental data measured at differing gaps.
2009-01-25