Collector-induced field emission triode

By positioning the gate below the tip in a vacuum triode, field emission can be initiated by the collector voltage V_c and the emission current can be modulated by the gate voltage V_g. Principle of operation is demonstrated for a single-tip, (100) monocrystalline tungsten field emitter triode. It is shown that the field at the emitter tip can be expressed by E=βV_g+γV _c. The parameters β and γ are obtained by fitting the emission currents to the Fowler-Nordheim equation. Their dependence as a function of gate-to-emitter distance is obtained for distances of 0.2, 0.25, and 0.3 cm and for two tip radii of approximately 40 and 2.5 Å. No gate current flows for moderate positive gate voltages of 40-60 V. With increasing gate voltages, gate currents are obtained for low collector voltages, similar to the gate-induced field emission triode