Silicon field emission arrays with atomically sharp tips: turn-on voltage and the effect of tip radius distribution

We report 1 nm tip radius, 1 μm gate-aperture silicon field emission arrays (FEAs) with turn-on voltage as low as 14 V. The low turn-on voltage is attributed to the small emitter tip radius, which was achieved by isotropic etching of silicon and low-temperature oxidation sharpening. Optimization of the oxidation sharpening process reduced the tip radius to less than 1 nm and was confirmed by transmission electron microscopy (TEM). The tip radius has a log-normal distribution with a peak at 0.75 nm, an expected value of 1.8 nm, and shape parameter of 0.74 nm. Current-voltage (I-V) characteristics of the field emission devices are in agreement with Fowler-Nordheim (FN) theory. The extracted tip radius using two-dimensional (2-D) numerical simulation showed good agreement with the TEM measurements.