A comparison of X-ray photoelectron spectroscopy and Auger electron spectroscopy depth profiles for magnesium implants

Abstract

The analysis of depth profiles when magnesium is present gives rise to several analytical problems with either X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES). With both techniques the relative sensitivity is low for the main transition usually employed, i.e., the 2s photoemission line in XPS and the KLL transition in electron-excited AES. With XPS, the Al X-ray-excited Mg KLL peak has a relative intensity that is greater than the 2s transition, but not with Mg radiation. The peak-to-peak height of the electron-excited AES peak can vary with the chemical state of Mg. Also, in some instances overlapping peaks can cause problems. In this study Mg was implanted into metal foils at various levels. Depth profiles were obtained with both XPS and AES, and the instrument-based quantitative analysis computer routines were used with slight modifications. It was found that each technique had its own set of advantages, and both approaches gave roughly comparable profiles. The estimated maximum amounts were below those anticipated from the implant conditions. As expected with XPS, chemical effects could easily be determined. However, a relative sensitivity factor was needed to use the X-ray-excited KLL Auger transition. With AES certain low-level contaminants were more easily detected and monitored. Overall, the XPS profiles appeared to offer better results in most respects for these systems. Other factors, e.g., time of analysis, data treatment methods, detection limits, etc., will be discussed also.