High current density Si field emission devices with plasma passivation and HfC coating

A novel self-aligned process was developed to fabricate gated Si field emission devices. At a gate voltage of 100 V, the emission cut-rent from an array of 100 tips increased from 284 to 460 mu A and the turn-on voltage decreased from 31 to 21 V after H-2 plasma passivation using an inductively coupled plasma (ICP) source for 2 min. The improvements correspond to a 1,28-eV reduction in the effective work function of the emitters and the instability of the emission current decreased from 11.25 to +/-0.25% after H-2 plasma passivation. Emitter tips were also coated with Mo silicide and HfC. The emission current increased from 230 mu A for uncoated emitters to 268 mu A for emitters coated with Mo silicide and 389 mu A for emitters coated with HfC, The turn-on voltage decreased from 50 to 41 and 25 V while the breakdown voltage increased from 126 to 129 and 143 V when Mo silicide and HfC were used for coating, respectively, which correspond to reductions of 0.95 and 2.23 eV, respectively, in the effective work function of the emitters. Single emitter tips have similar emission characteristics as high-density held emitter arrays? indicating excellent emission uniformity from the arrays.