Low voltage field emission of single Cu nanowire in air with nanoscale gaps for vacuum electronics

Abstract

Field emission applications to date including displays have featured electrode gaps in the micron scale or even larger. Devices such as vacuum field effect transistors demand smaller gaps for improved performance and continued scaling. The present work investigates nanoscale cathode–anode distances and evaluated field emission characteristics using a single Cu emitter. The gap was systematically varied between 20 and 80 nm with the aid of focused ion beam etching. Field emission was achieved at bias voltages below 5 V under atmospheric conditions with a 20 nm gap between the cathode and anode. The turn-on voltage was 1.75 V and the maximum current reached 32.5 nA at 5 V. The emission current is dependent on the cathode–anode distance and decreases exponentially with increasing distance. The nanoscale gap allows lower drive voltages than in previous studies while providing large emission currents for a single emitter.