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DS: Fachverband Dünne Schichten
DS 11: Thin Film Application
DS 11.4: Talk
Wednesday, March 29, 2023, 11:45–12:00, SCH A 315
All-oxide thin-film varactors with Mn- and Ni-doped (Ba,Sr)TiO3 for microwave applications — •Yating Ruan1, Stipo Matic2, Alexey Arzumanov1, Philipp Komissinskiy1, Rolf Jakoby2, and Lambert Alff1 — 1Advanced Thin Film Technology, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany — 2Microwave Engineering and Technology, Technische Universität Darmstadt, Darmstadt, Germany
With a trend toward miniaturization of modern electronics, tunable microelectronic devices operating over a wide range of frequencies are required for mobile communications, high-speed data connections with the upcoming 5G and Internet of Things (IoT) technologies.
Here we present all-oxide thin-film tuneable capacitors (varactors) with single-crystalline films of a tunable dielectric perovskite BaxSr1−xTiO3(BST) doped with Mn and Ni, grown epitaxially by pulsed laser deposition on a highly conducting thin-film oxide SrMoO3 bottom electrodes with a room-temperature resistivity of 30 µΩcm. A partial substitution of the tetravalent Ti at B-sites of the BST perovskite structure with Mn and Ni in a trivalent or divalent state decreases a concentration of oxygen vacancies in the BST, leading to a reduction of the leakage current density of the varactor by 5 orders of magnitude down to 1 A/m2. The low leakage current allows the thickness of the BST layers to go below 50 nm, enabling varactors tunable with low voltages.