Field Emitters Using Inverse Opal Structures

Electronics to be used in space must often perform in high temperature or radiation hard environments that render conventional solid-state technologies unable to meet mission requirements. As a result, microscale and nanoscale field emission devices are being explored as fundamental components of electronics capable of operating in these harsh environments. Wide scale implementation of these devices is hindered by the difficulty of fabricating large, mechanically stable, uniform arrays of sharp emitting tips. This work presents a scalable method to produce uniform arrays of field emitting tips. Polystyrene spheres are applied as a template for electrochemical deposition. An electrochemical etching process is developed to sharpen tips to a radius of curvature of 5–10 nm, optimizing them for field emission applications. The flexibility of the fabrication process allows for device optimization in terms of tip geometry, density, and constituent material to achieve high field enhancement factors, exceeding 100. Miniaturized field emitting diode and gated triode devices are fabricated. Finally, the electrochemically deposited material is used as a scaffold for the deposition of a refractory, low work function emitting layer, and the hybrid cathode is characterized as a field emitter at temperatures up to 300 ºC.