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.