Triode operation of a vacuum transistor

It is noted that, by recessing the gate below the emitter tip in a vacuum transistor, field emission can be initiated by the collector electrode and the current can be modulated by the gate electrode, similar to the classical thermionic triode. In this mode of operation, no gate current is obtained for negative and moderate positive gate voltages. To prove the principle of operation, a single-tip, single-crystal tungsten triode was fabricated and tested. The device, in the existing and in the micromachined version, can find applications in flat panel displays and in high-temperature pressure sensors. For the prototype device, pixel switching was obtained at a gate voltage change of 20 V, and for displacement/pressure applications a sensitivity of about 0.5 V/ mu m was obtained.<>