Field emitters and devices

A masking layer 405 is provided on selected areas of an electrode structure that is at least partly preformed, to define masked areas and unmasked areas (emitter cells 410). A first constituent with particles 408 and a second constituent 409 are then applied to the emitter cells 410 , and the particles 408 are selectively directed towards the bottoms of the emitter cells 410 - e.g. by electrophoresis. The masking layer 405 is then removed from the masked areas, together with any stray quantities of the first and second constituents 408, 409 on the masking layer 405. The first and second constituents 408, 409 are then processed (e.g. by curing) to create broad area field electron emission sites in desired locations of the electrode structure. An alternative embodiment uses an inkjet print head to selectively direct the particles (fig 6).