Extracting independently the work function and field enhancement factor from thermal-field emission of multi-walled carbon nanotube tips

We have characterized the emission properties of multi-walled carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition (CVD). Our characterizations have been conducted in the thermal-field (T-F) zone, a narrow transition zone between field emission and thermionic emission. The characteristic I-V curve in T-F zone, designated to Christov plot, is advantageous to extract independently the field enhancement factor and work function at the emitting site. Our approach is more reliable than Fowler-Nordheim (F-N) plot whose linear region provides the solution with two unknowns. On the other hand, the Christov plot in the T-F zone provides the solution with only the field enhancement factor. Using the general theory of electron emission, we find that the work function and field enhancement factor of the CVD-grown MWCNTs are 4.7 ± 0.4 eV and 3300 ± 200, respectively.