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Research

The members of SAWLab Saxony comprise scientists and technologists from IFW, different research institutions and industrial partners. Therewith our activities and competences span all topics related to acoustoelectronics: fundamentals, electrode and substrate materials, advanced thin film technologies and specific devices and acoustoelectronic applications.

The most important research and development topics cover:

Selected Results:

High-precision determination of acoustic material parameters of Cantangasite

Catangasite (Ca3TaGa3Si2O14, CTGS) is a very promising substrate material enabling long-term stable operation of piezoelectric devices in high-temperature environment. We thoroughly investigate this ordered member of langasite family crystals for application in future SAW-based sensors. In addition to compatibility to advanced electrode metallisations, this comprises high-precision characterisation of CTGS with respect to all acoustically relevant material properties i.e. complete stiffness, dielectric and piezoelectric tensors, mass density, conductivity and attenuation. As a result, an excellent matching full set of high-precision acoustic material parameters was extracted for CTGS at room temperature. These data and the associated temperature coefficients also determined, covering the very wide temperature range from 4.2K to 1200K, provide a versatile basis for the accurate design of CTGS-based devices operating between cryogenic and high temperatures.

A. Sotnikov, B. Sorokin, N. Asafiev, D. Shcherbakov, G. Kvashnin, Y. Suhak, H. Fritze, M. Weihnacht, H. Schmidt, IEEE Trans. UFFC (2021), URL.
Y. Suhak, W.L. Johnson, A. Sotnikov, H. Schmidt, H. Fritze, MRS Advances 4, 515 (2019), URL.
Y. Suhak, M. Schulz, W. L. Johnson, A. Sotnikov, H. Schmidt, H. Fritze, Solid State Ionics 317, 221 (2018), URL.
Y. Suhak, M. Schulz, A. Sotnikov, H. Schmidt, S. Ganschow, S. Sakharov, and H. Fritze, Ferroelectrics 537, 255 (2018), URL.
M. Weihnacht, A. Sotnikov, Y. Suhak, H. Fritze, H. Schmidt, Proc. 2017 IEEE Intern.  Ultrasonics Symp., 1-4 (2017), URL.

(top) Temperature dependency of the dielectric constant e33 for LGS (red) and SNGS (blue), (bottom) Temperature dependency of the elastic constant C66 for LGS (red) and SNGS (blue).

Elastic and dielectric properties of Langasite family crystals at low temperatures

Elastic and dielectric properties of La3Ga5SiO14 (LGS) and Sr3NbGa3Si2O14 (SNGS) piezoelectric crystals were studied at temperatures from 4.2 K to 300 K. The obtained results for the elastic constants (with the exception of C66 for LGS) are treated using Varshni approach based on the Einstein oscillator model. In LGS, the elastic constant C66 versus temperature shows a turnover point close to room temperature followed by a gradual decreasing with decreasing temperature down to 4.2K. It is also demonstrated, that high piezoelectric activity of the crystals keeps down to 4.2K which predestines clearly LGS and SNGS as promising materials for possible applications at cryogenic temperatures.

A.V. Sotnikov, E.P. Smirnova, H. Schmidt, M. Weihnacht, Phys. Solid State 57 (2015) 6, 1183-1187, URL.
A. Sotnikov, E. Smirnova, H. Schmidt, M.Weihnacht, J. Götze, S. Sakharov, Prodeedings of the 2015 Joint IEEE International Frequency Control Symposium and European Frequency and Time Forum, Denver, USA, 106-110 (2015), URL.

TEM image of a RuAl based film on CTGS with a combined AlN-SiO2 cover and barrier layer after annealing at 900 °C in high vacuum for 10 h.

RuAl-metallization systems for SAW-driven wireless, self-sufficient sensors for usage at 600°C and beyond

The intermetallic RuAl alloy with its high melting point and a strong oxidation and corrosion resistance is a very promising alternative thin film electrode material for usage in high-temperature sensor devices. Our research results demonstrate that a high-temperature stability of RuAl-based films on the high-temperature-stable piezoelectric substrate Ca3TaGa3Si2O14 (CTGS) can be realized in combination with AlN and SiO2 cover and barrier layer. Thin films stable up to 800 °C in air and 900 °C in high vacuum for at least 10 h were realized at IFW Dresden. The barrier layers between the CTGS and the RuAl film are essential to prevent degradation since the substrate emits oxygen at high temperatures.

M. Seifert, G.K. Rane, S. Menzel, T. Gemming, Journal of Alloys and Compounds 684, 510-517 (2016), URL.
M. Seifert, G.K. Rane, S. Menzel, T. Gemming, Journal of Alloys and Compounds 688, 228-240 (2016), URL.
M. Seifert, G.K. Rane, S. Oswald, S.B. Menzel, T. Gemming, Materials 10(3), 277 (2017), URL.
M. Seifert, G.K. Rane, S.B. Menzel, S. Oswald, T. Gemming, Journal of Alloys and Compounds 776, 819-825 (2019), URL.
M. Seifert, Materials 13 (7), 1605 (2020), URL.
M. Seifert, E. Brachmann, G.K. Rane, S.B. Menzel, S. Oswald, T. Gemming, Journal of Alloys and Compounds 813, 152107 (2020), URL.