XPS (X-ray Photoelectron Spectroscopy)
Also called ESCA – This method uses a focused x-ray beam to trigger photoelectrons from the surface of the sample, whose energy is measured and is characteristic of each element. By high energy resolution of the spectrometer even the binding state (e.g., oxidic, nitridic, etc.) can be measured. The method yields results from a surface layer of about 10nm depth. An advantage of the method is that it is very well quantifiable, so not only can say what is there, but also how much. The special feature of our XPS system is that it can perform the analysis in a spatially resolved manner, in areas that can be as small as 10 microns.
TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry)
This method uses ion beams to extract secondary ions from the sample surface. These are analyzed by a mass spectrometer and identified by accurate mass determination. Atoms and molecules are detected simultaneously and thus the substances present on the surface can be identified. The advantage of the method is besides the identification also the very high sensitivity. It is even possible to detect atomic monolayers on surfaces. At the same time, the method provides distribution images of the detected species, with a spatial resolution below one micrometer.
AES (Auger-electron spectrometer)
Named after the French Phyisker Pierre Auger, this is the method with the highest spatial resolution (about 10nm). Similar to a scanning electron microscope (SEM), the sample is irradiated with an electron beam. The released electrons are analyzed for their energy, which in turn is characteristic of the respective element. In contrast to the EDX analysis of a SEM, AES provides the very near-surface (about 5 nm) composition of the sample. The method is well quantifiable and therefore can deliver concentrations.
All three methods described above can also measure the depth profiles of layer systems with nanometer resolution by means of alternating sputter removal and analysis.