Resonant tunneling and extreme brightness from diamond field emitters and carbon nanotubes

Abstract

We report new results from field emission microscopy studies of multiwall carbon nanotubes and from energy spectrum measurements of beams from diamond field emitters. In both systems, we find that resonant tunneling through adsorbed species on the emitter surface is an important and sometimes dominant effect. For diamond emitters our observations include order-of-magnitude emission enhancement without spectral broadening, complex spectral structure, and sensitivity of that structure to the applied electric field. For carbon nanotubes we have observed electron beams from individual adsorbates which are estimated to approach the maximum beam brightness allowed by Pauli exclusion.

Influence of hydrogen on the thermionic electron emission from nitrogen-incorporated polycrystalline diamond films

“…[1][2][3][4] However, the emission decreases significantly when heated above $750-800 C and does not recover upon returning to lower temperatures. 5,6 This relatively low temperature limit for an otherwise promising rise in emission current with temperature diminishes the practical utility of diamond thermionic emitters.…”

R&D toward a compact high-brilliance X-ray source based on channeling radiation

“…The FE cathode is a critical element for producing low-emittance beams. Over the last few years, Vanderbilt has had an active program and have demonstrated near-quantum-degenerate emission from individual field-emission tips at a per-tip current as high as 15 µA [16,19]. The FE cathodes are of two types, gated and ungated.…”

“…Emittances within this order of magnitude have very recently been observed in photoinjectors [14]. Such emittances are also produced from field-emitter (FE) cathodes [16]. The latter type of cathodes presents the advantage of circumventing the use of a laser and are therefore a technology of choice for a compact and portable X-ray source.…”

Initial beam dynamics simulations of a high-average-current field-emission electron source in a superconducting radiofrequency gun

“…FE has gained much interest over the last decade owing to new development in field-emission displays and vacuum electronic devices. Additionally, FE has also been extensively investigated as electron sources for bright [4] or high-current [5] electron beams. The theory behind FE is well established and the current density is related to the applied electric field E z (t) via the Fowler-Nordheim's law [6,7]…”