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M. Weiss, H. Riedl, P.H. Mayrhofer, J. Fleig, A. Limbeck:
"Laser based elemental analysis of multilayer systems";
Talk: 20. Tagung Festkörperanalytik - 20th Conference on Solid State Analysis, Wien; 2019-07-01 - 2019-07-03; in: "Abstracts", (2019).

Many applications require the combination of different materials in the form of nano- to micrometer thick films. To understand and optimize the properties, the thickness of layers, as well as their composition from major constituents down to dopants and unwanted impurities must be known. Here we focus on two example classes of materials: Multilayer hard coatings, which allows to combine the benefits from two materials, like hardness and oxidation resistance and metal oxides for electrochemical applications.
In this work three laser-based methods are employed: Laser-ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), Laser induced breakdown spectroscopy (LIBS) and Laser ablation of solids in liquid (LASIL). All three are based on removing material from the sample by laser ablation and then analyze the ablated material by a hyphenated instrument (LA-ICP-MS and LASIL) or directly measure the characteristic element specific emission. Depth profiling with LA-ICP-MS as well as LIBS are established methods. A downside of both methods is their limited depth resolution as well as the cumbersome calibration, which usually requires the use of matrix matched standard materials. With LASIL it is possible to overcome these disadvantages. The ablation under liquid limits the removal of material, yielding a higher depth resolution, and enables to use liquid standards, which increases flexibility.
The recently introduced online LASIL procedure is further improved and adapted for depth profile measurements. Special emphasis is put on the quantification of the data for revealing the stoichiometry of the films as well as dopant and impurity levels. The results are compared to the other methods, where dried droplet approaches are used for quantification.

LASIL, ICP-OES, thin film analysis, stoichiometry

Project Head Andreas Limbeck:
online-LASIL