Berlin 2008 – scientific programme
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DS: Fachverband Dünne Schichten
DS 11: Thin Film Characterisation: Structure Analyse and Composition (XRD, TEM, XPS, SIMS, RBS, ...)
DS 11.2: Talk
Tuesday, February 26, 2008, 09:45–10:00, H 2013
Non-destructive probing of the chemical state of buried TiOx nanolayers — •Beatrix Pollakowski1, Burkhard Beckhoff1, Stefan Braun2, Peter Gawlitza2, Falk Reinhardt1, and Gerhard Ulm1 — 1Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin — 2Fraunhofer Institut Werkstoff- und Strahltechnik, Winterbergstr. 28, 01277 Dresden
Near edge x-ray absorption fine structure (NEXAFS) in combination with grazing incidence x-ray fluorescence (GIXRF) analysis provides a good approach for a depth-sensitive characterization of buried nanolayers with respect to both elemental composition and speciation. This idea offers the specific advantage of a high tunability of the information depth. The GIXRF regime implicates the occurrence of the x-ray standing waves (XSW) field above, at and below the surface affecting directly influence on the total fluorescence yield (TFY). The XSW field and the resulting mean information depth are dependent on incident angle and photon energy. The variation of the photon energy during a NEXAFS study requires to correct the incident angle to keep the mean information depth constant. The sample system consists of several 30 nm Ti nanolayers oxidized to different extents and being buried below 5 nm C. The results of angular corrected Ti L3,2 NEXAFS spectra exhibit an electronic structure presumably comparable to that measured in total electron yield (TEY) and confirm the potential of this method. GIXRF-NEXAFS provides a complementary approach to different non-destructive techniques based on electron detection, which can reach their limits for deeply buried thin layers.