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SEM micrographs of a double-gate FEA. (a) Top view and (c) cross-section. (b) Schematic diagram corresponding to the cross-section shown in (c). The shaded layers ( and ) are the thick insulators. and diameters are and , respectively. The inlay in (a) shows a transmission electron microscope (TEM) image of the emitter tip apex.
Schematic diagram of the experimental setup. The extracted electron beam is amplified by a microchannel plate biased to 0.7 kV given by and detected by the phosphor screen biased at a voltage of 5 kV. The currents , , and were simultaneously recorded. denotes the emission angle of the electron beam at the emitter surface.
Field-emission microscope images of electron beam at constant extraction bias of −80 V at collimation voltages of (a) , (b) −31, and (c) −61 V.
Absolute value of emitter current (open squares), net current (filled squares), extraction gate current (filled circles), and the collimation gate current (open circles) at various ’s for fixed at −80 V.
(a) Current density measured on the phosphor screen plotted against for fixed . The two inlaid pictures show the electron beam at of 0 V (bottom) and −69 V (top). (b) The relation between the emission angle and with the directions as defined in Fig. 3.
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