Relationship of the Distribution Thickness of Dielectric Layer on the Nano-Tip Apex and Distribution of Emitted Electrons 

Abstract

Field electron emission is the emission of electrons from the surface of a cathode under the influence of a high applied electrostatic field (typically about 3 V/nm) (Forbes et al., 2004; Mousa, 1996). The field electron emitter is particularly attractive as an electron source, due to its suitable emission properties and simple operating principle (Fischer et al., 2013). Tungsten is still one of the materials that are most frequently used for manufacturing field emitter tips (Latham, 1981; Marrese, 2000; Marulanda, 2010). Theoretically, cold field electron emission is the regime where (i) the electrons in the emitting region are effectively in local thermodynamic equilibrium (Mousa et al., 2012), and (ii) most electrons escape by deep tunneling from states close to the emitter’s Fermi level (Forbes et al., 2013). The first scientist to attempt to develop theory for cold field emission was Schottky (1923). Fowler and Nordheim (1928) developed the first appropriate theory for explaining field emission related phenomena. The first observation of what appears to be a field electron emission initiated electric discharge had been made by Winkler long before (Winkler & Gedanken, 1744). Electron emitter fabrication technology based on electrolytic etching (Melmed, 1991) has long been investigated and enhanced. This technology makes it possible to prepare electron emitters with a diameter in the nanometre range (Golubev & Shrednik, 2003). A wide range of composite micropoint cathodes has been manufactured in the authors’ group. The role of epoxylite resin in manufacturing composite emitters (Tungsten-Clark Electromedical Instruments Epoxylite resin [Tungsten/CEI-resin emitter]) have been to avoid degradation of the electron emitter tip due to ion sputtering processes during emission, to obtain an electron emitter with long lifetime, and improve the emission characteristics for the emitter (Mousa & Share, 1999; Mousa et al., 2001, 2012). In this work, various composite microemitters (Tungsten/ CEI-resin emitter) with different apex radii ranging from 112 to 287 nm were prepared. Scanning electron microscope (SEM) images were used to extract tip profiles (i.e., apex