Diamond cold cathode

Diamond cold cathodes have been formed by fabricating mesa-etched diodes using carbon ion implantation into p-type diamond substrates. When these diodes are forward biased, current is emitted into vacuum. The cathode efficiency (emitted current divided by diode current) varies from 2*10/sup -4/ to 1*10/sup -10/ and increases with the addition of 10/sup -2/-torr partial pressure of O/sub 2/ into the vacuum system. Current densities of 0.1 to 1 A-cm/sup -2/ are estimated for a diode current of 10 mA. This compares favorably with Si cold cathodes (not coated with Cs), which have efficiencies of approximately 2*10/sup -5/ and current densities of approximately 2*10/sup -2/ A-cm/sup -2/. It is believed that higher current densities and efficiencies can be obtained with more efficient cathode designs and an ultrahigh-vacuum environment.<
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