SiC emitters for nanoscale vacuum electronics: A systematic study of cathode–anode gap by focused ion beam etching

Abstract

Nanoscale vacuum electronics has been receiving much attention recently with the design and fabrication of vacuum field emission transistors and other devices. The performance and lifetime of these devices depend on the material choice for the emitters. Silicon carbide is a robust material with appealing work function and established fabrication processes. Field emission properties of SiC nanoemitters under different cathode–anode gaps are studied in this work with the aid of focused ion beam etching to control the gap precisely. When the electrode gap is as small as 20 nm, a considerable decrease in voltage and increase in field emission current are seen. When the electrode gap is decreased progressively, the emission current increases exponentially at a fixed collector voltage, and the absence of current saturation is ideal for device scaling. Simulations and Fowler–Nordheim equation are used to analyze the field emission characteristics. The emission is enhanced for both extremely short gaps and sharp emitter tips as expected. The present results for the diode-based system are useful for the design of future gated three terminal devices such as vacuum field emission transistors and field emission displays using SiC.