Epitaxial Growth of Sc0.09Al0.91N and Sc0.18Al0.82N Thin Films on Sapphire Substrates by Magnetron Sputtering for Surface Acoustic Waves Applications

Scandium aluminum nitride (ScxAl1-xN) films are currently intensively studied for surface acoustic waves (SAW) filters and sensors applications, because of the excellent tradeoff they present between high SAW velocity, large piezoelectric properties and wide bandgap for the intermediate compositions...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2020-08, Vol.20 (16), p.4630
Main Authors: Bartoli, Florian, Streque, Jérémy, Ghanbaja, Jaafar, Pigeat, Philippe, Boulet, Pascal, Hage-Ali, Sami, Naumenko, Natalya, Redjaïmia, A., Aubert, Thierry, Elmazria, Omar
Format: Article
Language:English
Subjects:
Acoustics
Composition
Coupling coefficients
Dielectric properties
Electromagnetic wave filters
Engineering Sciences
Epitaxial growth
hetero-epitaxial films
High temperature
Instrumentation and Detectors
Investigations
Magnetron sputtering
Materials
Molecular beam epitaxy
Organic chemicals
Phase transitions
Physics
Sapphire
SAW sensors
ScAlN thin films
Scandium
Sensors
Software
Spectrum analysis
sputtering
Surface acoustic wave devices
Surface acoustic waves
Thin films
Transmission electron microscopy
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Summary:Scandium aluminum nitride (ScxAl1-xN) films are currently intensively studied for surface acoustic waves (SAW) filters and sensors applications, because of the excellent tradeoff they present between high SAW velocity, large piezoelectric properties and wide bandgap for the intermediate compositions with an Sc content between 10 and 20%. In this paper, the growth of Sc0.09Al0.91N and Sc0.18Al0.82N films on sapphire substrates by sputtering method is investigated. The plasma parameters were optimized, according to the film composition, in order to obtain highly-oriented films. X-ray diffraction rocking-curve measurements show a full width at half maximum below 1.5°. Moreover, high-resolution transmission electron microscopy investigations reveal the epitaxial nature of the growth. Electrical characterizations of the Sc0.09Al0.91N/sapphire-based SAW devices show three identified modes. Numerical investigations demonstrate that the intermediate compositions between 10 and 20% of scandium allow for the achievement of SAW devices with an electromechanical coupling coefficient up to 2%, provided the film is combined with electrodes constituted by a metal with a high density.
ISSN:1424-8220
1424-8220
DOI:10.3390/s20164630