Quantitative surface microanalysis by Auger and x-ray photoelectron spectroscopy

Abstract

All materials and structures interact with their environment through surfaces, and consequently the importance of surface as opposed to bulk analysis is increasingly recognized in the design and development of advanced materials. Electron spectroscopic methods such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have the capability for microanalysis of the top few atom layers of solid samples. Traditionally, AES uses electron beam excitation, with correspondingly high spatial resolution, but was thought to give only limited chemical state information, whereas XPS was used for surface chemical analysis at an early stage of its development but with poor spatial resolution. Recent developments in both theory and instrumentation tend to blur this distinction, with chemical information available from AES together with a trend in XPS toward microarea analysis and, lately, imaging. In this article, the two techniques are compared and contrasted, with an emphasis on their microanalytical capability and potential for full quantification. Examples are taken from various areas of metallurgy and materials science.