Electron emission observations from as-grown and vacuum-coated chemical vapor deposited diamond

Field emission has been observed from chemical vapor deposited diamond grown on Mo and Si substrates. Emission was observed at fields as low as 20 kV/cm. The samples were tested in the as‐grown form, and after coating with thin films of Au, CsI, and Ni. The emission current was typically maximum at the onset of the applied field, but was unstable, and decreased rapidly with time from the as‐grown films. Thin Au layers, ∼15 nm thick, vacuum deposited onto the diamond samples significantly improved the stability of the emission current at values approximately equal to those from uncoated samples at the onset of the applied field. Thin layers of CsI, ∼5 nm thick, were also observed to improve the stability of the emission current but at values less than those from the uncoated samples at the onset of the applied field. While Au and CsI improved the stability of the emission, Ni was observed to have no effect.