Fabrication and characterization of volcano-shaped field emitters surrounded by planar gates

Micron-sized volcano field emitters have been developed and demonstrated using a new fabrication process. The key element of the process is the formation of the volcano-shaped thin-film emitter by sputtering technique, which results in very thin emission sites due to the shadowing effect of the masking oxide disk. For the emitter array with 1.5-mu m-diam gate apertures, an anode current of 0.1 mu A per emitter was obtained at the gate voltage of about 88 V. The emission performance is comparable to that of the cone-like held emitter with the same gate hole size. Since the field conversion factor of an off-axis rim must be much smaller than that of the apex of a cone emitter with the same effective emission radius, the comparable operating voltage between two types implies the formation of the rim emitters with extremely thin emission sites by the new process. (C) 1997 American Vacuum Society.