Triode emitters with well-structure cathode

The suppression of gate current was realized by introducing an extra conducting layer between gate-insulators and cathode layers. A new type of triode emitters were fabricated, in which carbon emitter layers were positioned at the central part of the well bottom formed in silicon well structures. The silicon well structure was formed using reactive ion etching (RIE). Because of the favorable field distribution using heavily doped η-type silicon, we were able to suppress the gate current almost completely.