Field Electron Emission from a Tungsten Cathode Coated with Silica

Abstract

The aim of this paper is to study the field electron emission of silicon dioxide-coated tungsten cathode. Tungsten tips of less than 100 nm radius were prepared by electrochemical etching. The size of silicon dioxide (silica) nanoparticles ranged from 3 to 15 nm. Field emission studies were conducted using a field emission microscope under high vacuum conditions. The images of the cathodes under investigation were taken using scanning electron microscopy. The results of the study of cathodes by energy-dispersive X-ray spectroscopy revealed tungsten as the dominant element with minimal silicon detected on the coated cathode surfaces. Murphy-Good plots were used to illustrate and analyze the current-voltage characteristics of the cathodes before and after coating. Moreover, patterns of electron emission both before and after the coating procedure were examined. The stability test of the emission current was performed on the composite cathode. The results indicate that the composite tungsten cathode performs better than the uncoated cathode, demonstrating increased emission current magnitude and enhanced stability of the emission current. The study presents silica nanoparticles as potential candidates for field emission sources coating across different applications.