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All-Oxide Varactor Electromechanical Properties Extracted by Highly Accurate Modeling Over a Broad Frequency and Electric Bias Range

Walk, Dominik ; Agrawal, Prannoy ; Zeinar, Lukas ; Salg, Patrick ; Arzumanov, Alexey ; Komissinskiy, Philipp ; Alff, Lambert ; Jakoby, Rolf ; Rupitsch, Stefan J. ; Maune, Holger (2021):
All-Oxide Varactor Electromechanical Properties Extracted by Highly Accurate Modeling Over a Broad Frequency and Electric Bias Range.
In: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 68 (8), pp. 2804-2814. IEEE, ISSN 0885-3010, e-ISSN 1525-8955,
DOI: 10.1109/TUFFC.2021.3070749,
[Article]

Abstract

Since the dielectric permittivity of ferroelectric materials depends on the electric field, they allow designing switchable and continuously tunable devices for adaptive microwave front ends. Part of the ongoing research is the field of all-oxide devices, where epitaxial oxide conductors are used instead of polycrystalline metal electrodes, leading to epitaxial ferroelectric layers and resulting in high device performance. In particular, they allow engineering the acoustic properties separated from the electric ones due to the structural similarity between the dielectric and conducting oxide films. Two major results are reported in this work. First, a highly accurate model for the microwave impedance of ferroelectric varactors is derived that tracks the superposition of induced piezoelectricity and field extrusion into the substrate caused by thin electrodes. In difference to previous works, this model covers both a wide frequency and biasing range up to 12 GHz and 100 V/ μ \textm . Second, the high model accuracy enables the determination of all relevant electric and mechanic properties based on a mere microwave characterization. This approach will be especially valuable when independent measurements of mechanical properties of the thin-film materials are impeded by a high integration of the devices. Though derived for all-oxide varactors, the presented model can as well be adapted for thin-film bulk acoustic wave resonators (FBARs) and varactors with conventional metal electrodes when eventual dead layers at the interface are modeled correctly.

Item Type: Article
Erschienen: 2021
Creators: Walk, Dominik ; Agrawal, Prannoy ; Zeinar, Lukas ; Salg, Patrick ; Arzumanov, Alexey ; Komissinskiy, Philipp ; Alff, Lambert ; Jakoby, Rolf ; Rupitsch, Stefan J. ; Maune, Holger
Title: All-Oxide Varactor Electromechanical Properties Extracted by Highly Accurate Modeling Over a Broad Frequency and Electric Bias Range
Language: English
Abstract:

Since the dielectric permittivity of ferroelectric materials depends on the electric field, they allow designing switchable and continuously tunable devices for adaptive microwave front ends. Part of the ongoing research is the field of all-oxide devices, where epitaxial oxide conductors are used instead of polycrystalline metal electrodes, leading to epitaxial ferroelectric layers and resulting in high device performance. In particular, they allow engineering the acoustic properties separated from the electric ones due to the structural similarity between the dielectric and conducting oxide films. Two major results are reported in this work. First, a highly accurate model for the microwave impedance of ferroelectric varactors is derived that tracks the superposition of induced piezoelectricity and field extrusion into the substrate caused by thin electrodes. In difference to previous works, this model covers both a wide frequency and biasing range up to 12 GHz and 100 V/ μ \textm . Second, the high model accuracy enables the determination of all relevant electric and mechanic properties based on a mere microwave characterization. This approach will be especially valuable when independent measurements of mechanical properties of the thin-film materials are impeded by a high integration of the devices. Though derived for all-oxide varactors, the presented model can as well be adapted for thin-film bulk acoustic wave resonators (FBARs) and varactors with conventional metal electrodes when eventual dead layers at the interface are modeled correctly.

Journal or Publication Title: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Journal volume: 68
Number: 8
Publisher: IEEE
Uncontrolled Keywords: Impedance;Varactors;Electrodes;Microwave measurement;Mathematical model;Substrates;Microwave communication;Ferroelectric films;modelling;piezoelectricity;thin film circuits;tunable microwave components
Divisions: 18 Department of Electrical Engineering and Information Technology
18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics > Microwave Engineering
18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics
Date Deposited: 01 Nov 2021 11:02
DOI: 10.1109/TUFFC.2021.3070749
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