Double-gate field emitter arrays: aperture size dependence of electron beam collimation characteristics

Full text: An on-the-chip collimation gate electrode can increase the brightness of the electron beam produced by a microfabricated field-emitter array cathode. Recently, we have developed a focused ion beam assisted process to define size and geometry of the collimation gate aperture flexibly and showed an order of magnitude increase of the electron beam brightness by adjusting the ratio of the gate aperture openings. Here we report the aperture size dependence of the electron beam collimation characteristics and the experimental demonstration that noteworthy collimation can only be achieved in a relatively small parameter range. Furthermore, a comparison of experimental data with numerical simulations, including space-charge effects, will be discussed. (author)