Microstructure and dielectric properties of piezoelectric magnetron sputtered w-Sc{sub x}Al{sub 1-x}N thin films

Journal Article · Tue May 01 04:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4714220· OSTI ID:22038951

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas; Jensen, Jens; Persson, Per O. A.; Birch, Jens; Hultman, Lars ^[1]; Matloub, Ramin; Muralt, Paul ^[2]; Kim, Yunseok ^[3]

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1. Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping (Sweden)
2. Ceramics Laboratory, Ecole Polytechnique Federale de Lausanne EPFL, Lausanne (Switzerland)
3. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

Piezoelectric wurtzite Sc{sub x}Al{sub 1-x}N (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al{sub 2}O{sub 3}(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 deg. C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 deg. C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x {>=} 0.2 when substrate temperature is increased from 400 to 800 deg. C. The piezoelectric response of epitaxial Sc{sub x}Al{sub 1-x}N films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

• OSTI ID: 22038951
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 9 Vol. 111; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
CRYSTAL STRUCTURE
DENSITY FUNCTIONAL METHOD
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
EPITAXY
INTERFEROMETRY
LAYERS
LEAKAGE CURRENT
MICROSTRUCTURE
PIEZOELECTRICITY
SCANDIUM NITRIDES
SPUTTERING
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY