SKM 2023 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 11: Thin Film Application

DS 11.4: Vortrag

Mittwoch, 29. März 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 Ba_xSr_1−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.