Effect of band structure on field emission of crystalline graphite

The field emission of crystalline AAA graphite is studied within a simple analytical approach with account of the exact dispersion relation near the Fermi level. The emission current is calculated for two crystal orientations with respect to the applied electric field. It is found that the exponent of the Fowler-Nordheim equation remains the same while the preexponential factor is markedly modified. For both field directions, the linear field dependence is found in weak fields and the standard quadratic Fowler-Nordheim behavior takes place in strong fields. A strong dependence of the emission current from the interlayer distance is observed. As an illustration of the method the known case of a single-walled carbon nanotube is considered.