Planar Cold Cathodes

Abstract

Publisher Summary A planar cathode is a thin-film emitter deposited on a conducting surface. It emits electrons when an electric field is applied by an anode separated from the film front surface by a vacuum gap. This chapter discusses thin film and ultra-thin film planar cathodes with effective low work function. It focuses on basic principles underlying the electron emission to avoid the misinterpretation of experimental results. The chapter describes the two basic mechanisms for extracting electrons from solids to determine the precise limits of the present theoretical approaches—both by analytical and numerical simulations. In the chapter, scanning anode field emission microscopy (SAFEM) is described and experimental results with flat cathodes are presented in a later section with their field emission characteristic analyzed by SAFEM. Spindt field emission arrays (FEAs), which are the heart of field emission displays (FEDs), are basically microfabricated molybdenum tips in gated configuration that use the local field enhancement at the apex of each microtip in front of a gate located at a microscale distance to lower the threshold voltage (100 V), thus enabling field emission.