Emission characteristics of silicon vacuum triodes with four different gate geometries

Arrays of 10×10, 30×30, and 50×50 phosphorus-doped 0.005-0.025 Ω-cm, monocrystalline silicon field emitters have been fabricated with an emitter height of approximately 4.5 μm, a cone angle of 110°, and four gate openings ranging from 1.8 to 5.3 μm. The placement of the rims of the gates range from coplanar with the apexes of the emitters for the 1.8-μm devices to fully recessed for the 5.3-μm devices. The devices have been characterized in terms of geometry-dependent β factors, scaling of emission currents with array size, temperature dependency from room temperature to 48 K, pressure dependency from 2.5×10^-9 to 0.8×10^-5 torr, current fluctuations at room temperature and at 48 K, and image formation. All of the measurements have been performed by operating the devices in the gate-induced field emission mode