XPS X-ray Photoelectron Spectroscopy

In this technique the sample is irradiated with monochromatic X-rays and the resulting intensities and kinetic energies of the photoelectrons ejected from the surface are recorded. From this it is possible to calculate the corresponding binding energies from knowledge of the incident photon energy and the work function of the spectrometer. Since the binding energies of core electrons are characteristic for elements in a certain chemical environment, XPS allows for a determination of the atomic compositions of a sample. The shifts in the binding energies also provide information regarding the “chemical state” of elements being analysed. XPS depth profiling analysis is carried out by sequential sputter erosion and acquisition of spectra which produces quantitative data regarding the composition of a film as a function of depth. Non destructive depth profiling is also possible using Angle Resolved XPS (AR XPS) by collecting the photoelectrons as a function of (a minimum of five) different take off angles. These will provide a depth profile from the near surface region of the film, including "chemical state" information in a non damaging manner, since the process does not involve sputtering. The important application areas of AR XPS are non destructive depth profiling of ultra thin oxides e.g. oxynitrides and high-k dielectrics. General applications of XPS include quantitative measurement of composition of organic and inorganic samples, determination of "chemical states" (e.g. oxidation state) and depth profiling of coatings. The detection limit of the technique is ~0.1 atomic%.

For more information on XPS X-ray Photoelectron Spectroscopy talk to Aystorm Scientific Ltd