DIAMOND GRIT-BASED FIELD-EMISSION CATHODES

This letter describes the fabrication and operation of diamond grit ga ted cathodes. The structure is similar to Spindt-type cathode, but the field emission cone is replaced with a more planar diamond grit layer 50 to 200 nm thick. Although the minimum lithographic dimension of th ese cathodes is from 1 to 5 mu m, these devices have exceptionally low turn-on voltages, 5 to 7 V. Cathode current noise is less than 2.5% r ms with a maximum absolute current variation of 6.7% over a 6 h period . These de,ices can operate in pressures of nitrogen above 133 Pa (1 T orr). Although operation in 6.6 x 10(-2) Pa (5 x 10(-4) Torr) with mor e reactive gasses, O-2 or H2S, degrades performance, the cathodes reco ver when the pressure is reduced to less than or equal to 1.3 x 10(-4) Pa (1 x 10(-6) Torr). Gate current varies from 0.2 to 100 times the e mitted current and depends on the technique used to deposit the diamon d grit. High current densities (>10 A cm(-2)) low gate voltages (<50 V ), low emission noise, excellent longevity, temporal uniformity, and e ase of fabrication make these devices potential cathodes for flat pane l displays. However, excessive gate current and unsatisfactory process ing reproducibility at present limit their general application.