The field emission planar electron emitter device is disclosed that has an emitter
electrode, an extractor electrode, and a planar emitter emission layer, electrically
coupled to the emitter electrode and the extractor electrode. The planar electron
emitter is configured to bias electron emission in a central region of the emission
layer in preference to an outer region thereof. One structural example that provides
this biasing is achieved by fabricating the planar emitter emission layer so that
it has an outer perimeter that is thicker in depth than at an interior portion
of the planar emitter emission layer, which reduces electron beam emission at the
outer perimeter when an electric field is applied between the emitter electrode
and the extractor electrode. The electric field draws emission electrons from the
surface of the planar emitter emission layer towards the extractor electrode at
a higher rate at the interior portion than at the outer perimeter. The planar electron
emitter device further includes a focusing electrode electrically coupled to the
planar electron emitter.