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

Tungsten-coated silicon-based field emitters with a sandwich structure consisting of a cathode tip–insulator–metal gate, were fabricated using microfabrication technology. The radii of the tungsten-coated tips were approximately 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 metal gate aperture was approximately 1 μm. The silicon dioxide insulating layer was about 1 μm thick. Field emission studies were carried out under ultra-high vacuum conditions. The lowest turn on voltage of the emitter arrays was 30 V. Current–voltage characteristics were studied and Fowler–Nordheim plots confirmed field emission behavior. Emission current of over 15 μA was recorded from a single field emitter. Current stability showed fluctuations of up to 60% of its maximum when emission was initiated but improved to 20% after 1–2 h of operation. Emission current did not decrease when the pressure changed from 10−10 to 1×10−6 mbar.