Nanoscale silicon field emitter arrays with self-aligned extractor and focus gates.

Out-of-plane focusing is essential for electron beam collimation in gated field emission sources. The focus electrode redirects electrons emitted by the tip with a wide angle towards the central axis, resulting a small focal spot at the anode. Here, we demonstrate for the first time, very high density (10 emitters/cm) arrays of double-gated field emission electron sources with self-aligned apertures and integrated nanowire current limiters.