Gated Micron-size Electron Field Emitters

Summary: A new micro vacuum-tube technology has emerged during the past few years which has application in flat panel displays, high-frequency amplifier tubes, and in other devices and systems using electron beams. The heart of this new technology is a micron-size electron field emitter consisting of an electron source and a closely-spaced "gate" or "grid" electrode. A large-area array of such closely-spaced gated emitters would serve as a distributed electron source for a flat CRT image display panel, for example'. A procedure has been developed for making arrays of such gated electron field emitters from silicon with some advantages over similar processes developed elsewhere%3. One micron-high emitters are made with radii as small as 1 nm4, and with self-aligned flat gate electrodes with low capacitance (30 pF/mm2) and with the circular gate opening controlled to sub-micron diameter independently of the tip height. The process is compatible with silicon tips coated with a thin metal film or other low work function material. Emission measurements show expected Fowler-Nordheim behavior, with the FowlerNordheim curves (W2 vs. 1/V) parallel but displaced along the 1/V axis for different tips. e field factor K (where E = K x V) is derived from the measured slope, and the emission area is derived from K, the Fowler-Nordheim equation, and an assumed work hction. Analysis of one such curve shows a high field factor of 3-7 x 105 cm" I, and an emission area of 1.2-1.6 x 10- l1 cm2 (corresponding to a range of work functions from 3.0 to 5.0 ev) which suggests emission from a region larger than just the emitter tip.