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DF: Fachverband Dielektrische Festkörper
DF 17: Focused Session on GHz Dielectrics: Materials for Mobile Communication II (DF with HL/MM)
DF 17.3: Talk
Thursday, March 19, 2015, 15:50–16:10, EB 407
Microwave electric properties of thin-film BaxSr1−xTiO3 varactors with highly-conducting epitaxial SrMoO3 oxide electrodes — •Arzhang Mani1, Aldin Radetinac1, Mohammad Nikfalazar2, Sergiy Melnyk2, Philipp Komissinskiy1, Yuliang Zheng2, Rolf Jakoby2, and Lambert Alff1 — 1Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Deutschland — 2Institut für Mikrowellentechnik und Photonik, Technische Universität Darmstadt, 64283 Darmstadt, Deutschland
We present high-frequency properties of MIM thin-film varactors with dielectric BaxSr1−xTiO3 (x=0.4, 0.5, 0.6). Single crystalline BaxSr1−xTiO3 layers were grown epitaxially on highly-conducting oxide SrMoO3 electrodes with room-temperature resistivity of 30 µΩ· cm. Au/Pt top electrodes were deposited by magnetron sputtering on top of the BaxSr1−xTiO3 / SrMoO3 heterostructures and patterned with photolithography and lift-off. Influence of Ba content (x), thickness of BaxSr1−xTiO3 layer, and size of the top electrodes on performance of the varactors were investigated in the frequency range of 100 MHz to 10 GHz. Capacitance of 15 pF, quality factor of 15, and tunability of 40% at 0.3 MV/cm were obtained at 100 MHz. The obtained results suggest a high potential of the oxide perovskite electrode material SrMoO3 [1] for fabrication of highly tunable varactors in microwave applications.
[1] A. Radetinac et al., Appl. Phys. Lett. 105, 114108 (2014).