Effect of UV light irradiation on charge neutralization in XPS measurements

TL;DR

Introducing UV light irradiation during XPS measurements stabilizes spectra by reducing surface charging effects, offering an effective alternative to traditional neutralization methods for insulator surfaces.

Contribution

This study demonstrates that UV light irradiation can effectively neutralize surface charge in XPS, improving spectral stability and uniformity, and presents it as a promising alternative neutralization technique.

Findings

UV irradiation reduces spectral peak shifts and deformation.

UV-assisted neutralization is as effective as dual beam methods.

Adsorption of UV-excited photoelectrons aids charge neutralization.

Abstract

When XPS analyses are performed on insulator surfaces, shift and deformation of spectra peaks typically take place due to the surface charging. To achieve reliable XPS measurements, neutralization techniques have been widely adopted but their effectiveness are still limited, and thus, new neutralization technologies are urgently needed. Here, stable XPS spectra in which all the peaks undergo a reduced and nearly constant shift without significant deformation and broadening were obtained by introducing the UV light irradiation, implying that the introduction of the UV light can not only greatly attenuate the strength but also significantly improve both the temporal stability and the spatial uniformity of the surface charging during XPS measurements. This phenomenon, referred to as UV-assisted neutralization in this article, was found as effective as the most commonly used dual beam charge neutralization. Further observations show that the suppression of the charging issue comes from the adsorption of the UV-excited photoelectrons onto the X-ray irradiation region. This neutralization method, combined with the binding energy referencing, can be expected to become a promising alternative technique for solving the charging issues in XPS measurements.