Diamond grit-based field emission cathodes

This letter describes the fabrication and operation of diamond grit gated 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 these cathodes is from 1 to 5 μm, these devices have exceptionally low turn-on voltages, 5 to 7 V. Cathode current noise is less than 2.5% rms with a maximum absolute current variation of 6.7% over a 6 h period. These devices can operate in pressures of nitrogen above 133 Pa (1 Torr). Although operation in 6.6×10/sup -2/ Pa (5×10/sup -4/ Torr) with more reactive gasses, O₂ or H₂S, degrades performance, the cathodes recover when the pressure is reduced to /spl les/1.3×10/sup -4/ Pa (1×10/sup -6/ Torr). Gate current varies from 0.2 to 100 times the emitted current and depends on the technique used to deposit the diamond grit. High current densities (>10 A cm/sup -2/), low gate voltages (<50 V), low emission noise, excellent longevity, temporal uniformity, and ease of fabrication make these devices potential cathodes for flat panel displays. However, excessive gate current and unsatisfactory processing reproducibility at present limit their general application.