CALCULATION OF ELECTRON FIELD-EMISSION FROM DIAMOND SURFACES

The electron field emission from diamond surfaces is investigated theoretically using a model consisting of the projection of the energy-band surfaces in the 〈111〉, 〈110〉, and 〈100〉 emission directions. The effect of the negative electron affinity, the band bending, the image interaction, and surface states are examined in detail. It is found that the tunneling from the bulk conduction and valence bands is negligible in p-type diamond. While emission from surface states located about 1 eV below the conduction band has sufficient transmission probability to produce currents observed in experiments, there is no obvious transport mechanism in intrinsic, doped, or polycrystalline diamond to sustain a direct field emission current. We postulate two subbands in the intrinsic band gap, which may be generated by defects or impurities. With reasonable band parameters, the calculated j-F characteristics agree with experimental data.