Fabrication of Enhanced Diamond Field Emitter Arrays for THz Vacuum Tubes

Many applications for miniaturized millimeter/THz-wave tubes and electron accelerators demand compact size of source, high emission currents, and small emittance. We propose that diamond field emitter arrays (DFEA) can be used as an electron beam source of those tubes and accelerators. DEFA cathodes have 10–20 nanometer sharp tips on top of the micrometer scale of pyramids. Those cathodes have high thermal conductivity and can operate in poor vacuum
$(< 10^{5} \text{Torr})$
that matches well for compact millimeter/THz-wave sources. Using mold-transfer method and electron beam lithography (EBL) skills, we improve the current fabrication techniques [1] to establish precise and uniform emission tip morphology. With 2 nm resolution from the EBL, we are capable of fabricating 10 nm single tip on each pyramid in the array of
$6 \mathrm{x}100$
. Also, with enhanced high quality of the synthetic nitrogen-doped ultrananocrystalline diamond from the Michigan State University, each emitter will provide higher pet-tip current (
$> 15\mu \mathrm{A}$
per-tip), and total emission current will be about 9 mA. We will present the details of the fabrication process using EBL skills.