Characterization of Tungsten Surfaces by Simultaneous Work Function and Secondary Electron Emission Measurements

Abstract

The changes of the work function (Phi) and the secondary electron emission (SEE) of oxygen covered polycrystalline tungsten occurring after ion sputtering and heat treatments have been investigated. The chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS), and the electron emission properties by work function spectroscopy (WFS). We observed in what manner the chemical changes of the surface are reflected in the work function and SEE. The simultaneous change of Phi and SEE in the case of oxygen covered tungsten have been pointed out and a direct relationship between them can be supposed.

Nitrogen‐Doped Tungsten Oxide Nanowires: Low‐Temperature Synthesis on Si, and Electrical, Optical, and Field‐Emission Properties

“…A and B are constants corresponding to 1.56×10 −10 [AV −2 (eV)] and 6.83×10 3 [V (eV −3/2 ) (μm −1 )], respectively. The field‐enhancement factor β reflects the degree of field emission for the tip shape on a planar surface, and can be estimated from the slope (− BΦ 3/2 / β ) of the Fowler–Nordheim plot, assuming the work function of WO 3 to be 5.7 eV 32a,b. Two straight lines can be unambiguously found and reflect the different β values at the high‐ and low‐field regions.…”

Tungsten Oxide Nanowires Grown on Carbon Cloth as a Flexible Cold Cathode

“…The work function of TONWs was assumed to be ∼ 5.6 eV. [ 29 ] The fi eld enhancement factor β , estimated from the slope of the FN plot under low electric fi eld is about 1657.…”

A xenon gas purity monitor for EXO

“…In the absence of space charge, the thermionic current density emitted from a heated tungsten surface is given by Richardson's law: I ∼ T 2 e −Φ/kT , where Φ is the work function of the filament surface. The work functions of tungsten and tungsten oxide have been measured to be 4.5 eV and 5.59-5.7 eV respectively [8,9]. These values imply that a fully oxidized filament will suffer a reduction factor of 1000 to 6000 in thermionic emission compared to a pure tungsten surface.…”