Investigation of an electron‐beam microgun using a microtips array Available to Purchase

A microtip field‐emission electron microgun of a few cm³ has been developed for a novel type of semiconductor laser. The electron source is provided by an array of a field emissive microtips cathode each of 1.4 μm base diameter. The source current–voltage characteristic has been determined and its geometrical characteristics have been measured by collecting electrons on a phosphor screen in a region of constant electric field. We have observed that about 100 μA are typically emitted for gate‐cathode voltage (V_GC) of 80 V with a half‐aperture angle of 28°. Beam focusing is then realized by two electrostatic lenses: a ‘‘thin hole lens’’ and a quadrupole lens. Using a cathode a 70×500 μm² rectangular spot on a 10 kV biased anode has been obtained which yields a power density of about 3 kW/cm². Less than 20% of the total electron beam (current) is lost in the electrostatic optics.