| 摘要 |
Applicants have discovered methods for making electron emitters using commercially available diamond particles treated to enhance their capability for electron emission under extremely low electric fields. Specifically, applicants have discovered that electron emitters comprising ultra-fine (5-10,000 nm) diamond particles heat-treated by a hydrogen plasma, can produce electron emission current density of at least 0.1 mA/mm2 at extremely low electric fields of 0.5-1.5 V/ mu m. These field values are about an order of magnitude lower than exhibited by the best defective CVD diamond and almost two orders of magnitude lower than p-type semiconducting diamond. Emitters are preferably fabricated by suspending the ultra-fine diamond particles, preferably in the nanometer size range, in an aqueous solution, applying the suspension as a coating onto a conducting substrate such as n-type Si or metal, and then subjecting the coated substrate to a plasma of hydrogen, preferably at temperatures above 300 DEG C. for a period of 30 minutes or longer. The resulting emitters show excellent emission properties such as extremely low turn-on voltage, good uniformity and high current densities. It is further found that the emission characteristics remain the same even after the plasma treated diamond surface is exposed to air for several months.
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