Field emission studies of tungsten-coated silicon-based field emitters

Tungsten-coated silicon-based field emitters with a sandwich structure cons isting of a cathode tip-insulator-metal gate, were fabricated using microfa brication technology. The radii of the tungsten-coated tips were approximat ely 30 nm. Each field emitter had a volcano-shaped metal gate aperture with a cathode tip protruding out in the center. The diameter of the smallest m etal gate aperture was approximately 1 mu m The silicon dioxide insulating layer was about 1 mu m thick. Field emission studies were carried out under ultra-high vacuum conditions. The lowest turn on voltage of the emitter ar rays was 30 V. Current-voltage characteristics were studied and Fowler-Nord heim plots confirmed field emission behavior. Emission current of over 15 m u A was recorded from a single field emitter. Current stability showed fluc tuations of up to 60% of its maximum when emission was initiated but improv ed to 20% after 1-2 h of operation. Emission current did not decrease when the pressure changed from 10-10 to 1 x 10-6 mbar. (C) 1999 Elsevier Science B.V. All rights reserved.