Physical properties of thin-film field emission cathodes with molybdenum cones

Abstract

Field emission cathodes fabricated using thin-film techniques and electron beam microlithography are described, together with effects obtained by varying the fabrication parameters. The emission originates from the tip of molybdenum cones that are about 1.5 μm tall with a tip radius around 500 Å. Such cathodes have been produced in closely packed arrays containing 100 and 5000 cones as well as singly. Maximum currents in the range 50–150 μA per cone can be drawn with applied voltages in the range 100–300 V when operated in conventional ion-pumped vacua at pressures of 10−9 Torr or less. In the arrays, current densities (averaged over the array) of above 10 A/cm2 have been demonstrated. Life tests with the 100-cone arrays drawing 2 mA total emission (or 3 A/cm2) have proceeded in excess of 7000 h with about a 10% drop in emission current. Studies are presented of the emission characteristics and current fluctuation phenomena. It is tentatively concluded that the emission arises from only one or a few atomic sites on the cone tips.

Growth of Large-Area Aligned Molybdenum Nanowires by High Temperature Chemical Vapor Deposition: Synthesis, Growth Mechanism, and Device Application

“…A turn-on filed of 5.0 MV/m and a threshold field of 9.9 MV/m were obtained, these values are much lowers then that of the classical Spindt Mo tips. 15 The Fowler-Nordheim (F-N) plot [top-left inset in Figure 7a] exhibits linear dependence, indicating that the emission is consistent with the FN mechanism. The bottom-right inset in Figure 7a is the CCD images of the sample and the spatial distribution of the emission sites (11.2 MV/m and 20 mA/cm 2 ).…”

Field electron emission from individual diamond cone formed by plasma etching

“…It indicates that the emission from these single diamond cones is stable after the surface stabilization process, except at rather low voltage. Using simplified FN equation, 17 the slope S for FN plot at the stable emission region is given as…”

Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

“…10 Field emitter arrays (FEAs) with on-chip electron extraction gate electrodes G ext , which combine the electron emission of thousands to millions of nanotips, have been explored for high current generation with a wide variety of materials. 7,[11][12][13][14] To generate high brightness beams with a small transverse electron velocity spread, however, it is crucial to add an on-chip gate electrode G col for the collimation of individual field emission beamlets. These so-called double-gate FEAs have been proposed as high current and high brightness cathodes 15,16 and have been actively studied.…”