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    XPS chemical state analysis of sputter depth profiling measurements for annealed TiAl-SiO2 and TiAl-W layer stacks
    (Chichester [u.a.] : Wiley, 2020) Oswald, Steffen; Lattner, Eric; Seifert, Marietta
    For the application of surface acoustic wave sensors at high temperatures, both a high-temperature stable piezoelectric substrate and a suitable metallization for the electrodes are needed. Our current attempt is to use TiAl thin films as metallization because this material is also known to be high temperature stable. In this study, Ti/Al multilayers and Ti-Al alloy layers were prepared in combination with an SiO2 cover layer or a W barrier layer at the interface to the substrate (thermally oxidized Si or Ca3TaGa3Si2O14) as an oxidation protection. To form the high-temperature stable γ-TiAl phase and to test the thermal stability of the layer systems, thermal treatments were done in vacuum at several temperatures. We used X-ray photoelectron spectroscopy (XPS) sputter depth-profiling to investigate the film composition and oxidation behavior. In this paper, we demonstrate how the semiautomatic peak fitting can help to extract beside the elemental information also the chemical information from the measured depth profiles. © 2020 The Authors. Surface and Interface Analysis published by John Wiley & Sons Ltd
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    New electronic device for driving surface acoustic wave actuators
    (Amsterdam : Elsevier, 2009) Brünig, R.; Mensel, K.; Kunze, R.; Schmidt, H.
    Surface acoustic wave (SAW) actuators are driven by a high frequency signal. The frequency range for an ideal SAW-generation is usually very narrow banded and may shift depending on various environmental conditions. We present a new electronic device which self-aligns to the optimal excitation frequency within a wide range. Any kind of SAW-actuator can be used. The device continuously scans a certain frequency range and characterizes the SAW-component. The ideal excitation frequency is then determined and used to drive the SAW-device. In case of changes like loading conditions or temperature variations the device automatically readjusts to the optimal frequency and prevents possible damage of the device or actuator in case of an error. © 2009.