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  • 1.
    Ben Sedrine, Nabiha
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. University of Aveiro, Portugal; University of Aveiro, Portugal.
    Zukauskaite, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Fraunhofer Institute Appl Solid State Phys, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schoeche, S.
    University of Nebraska, NE 68588 USA.
    Schubert, M.
    University of Nebraska, NE 68588 USA.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Infrared dielectric functions and optical phonons of wurtzite YxAl1-xN (0 less than= x less than= 0.22)2015Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 48, nr 41, s. 415102-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    YAlN is a new member of the group-III nitride family with potential for applications in next generation piezoelectric and light emitting devices. We report the infrared dielectric functions and optical phonons of wurtzite (0001) YxAl1-xN epitaxial films with 0 less than= x less than= 0.22. The films are grown by magnetron sputtering epitaxy on c-plane Al2O3 and their phonon properties are investigated using infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The infrared-active E-1(TO) and LO, and the Raman active E-2 phonons are found to exhibit one-mode behavior, which is discussed in the framework of the MREI model. The compositional dependencies of the E-1(TO), E-2 and LO phonon frequencies, the high-frequency limit of the dielectric constant, epsilon(infinity), the static dielectric constant, epsilon(0), and the Born effective charge Z(B) are established and discussed.

  • 2.
    Ben Sedrine, Nebiha
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Zukauskaite, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bandgap Engineering and Optical Constants of YxAl1-xN Alloys2013Inngår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 52, nr 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study wurtzite Yx Al1-xN (0 andlt;= x andlt;= 0:22) films with (0001) orientation deposited by magnetron sputtering epitaxy on Si(100) substrates and we determine the alloys band gap energies and optical constants. Room temperature spectroscopic ellipsometry (SE) is employed in the energy range from 1 to 6.3 eV, and data modeling based on the standard dielectric function model is used. As a result of the SE data analysis the Yx Al1-xN refractive index and extinction coefficient are determined. The band gap of Yx Al1-xN is found to decrease linearly from 6.2 eV (x=0) down to 4.5 eV (x=0:22). We further observe an increase of the refractive index with increasing Y content; from 1.93 to 2.20 (at 2 eV) for x=0 and 0.22, respectively, reflecting the increase in material density.

  • 3.
    Höglund, Carina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Bareño, Javier
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Czigány, Zsolt
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Wingqvist, Gunilla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Zukauskaite, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Wurtzite-structure Sc1-xAlxN solid solution films grown by reactive magnetron sputter epitaxy: structural characterization and first-principles calculations2010Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 107, nr 12, s. 123515-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AlN(0001) was alloyed with ScN with molar fractions up to ~22%, while retaining a singlecrystal wurtzite (w-) structure and with lattice parameters matching calculated values. Material synthesis was realized by magnetron sputter epitaxy of thin films starting from optimal conditions for the formation of w-AlN onto lattice-matched w-AlN seed layers on Al2O3(0001) and MgO(111) substrates. Films with ScN contents between 23% and ~50% exhibit phase separation into nanocrystalline ScN and AlN, while ScN-rich growth conditions yield a transformation to rocksalt-structure Sc1-xAlxN(111) films. The experimental results are analyzed with ion beam analysis, X-ray diffraction, and transmission electron microscopy, together with ab-initio calculations of mixing enthalpies and lattice parameters of solid solutions in wurtzite, rocksalt, and layered hexagonal phases.

  • 4.
    Kerdsongpanya, Sit
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Van Nong, Ngo
    Technical University of Denmark.
    Pryds, Nini
    Technical University of Denmark.
    Zukauskaite, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Wingqvist, Gunilla
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Anomalously high thermoelectric power factor in epitaxial ScN thin films2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, nr 23, s. 232113-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermoelectric properties of ScN thin films grown by reactive magnetron sputtering on Al2O3(0001) wafers are reported. X-ray diffraction and elastic recoil detection analyses show that the composition of the films is close to stoichiometry with trace amounts (similar to 1 at. % in total) of C, O, and F. We found that the ScN thin-film exhibits a rather low electrical resistivity of similar to 2.94 mu Omega m, while its Seebeck coefficient is approximately similar to-86 mu V/K at 800 K, yielding a power factor of similar to 2.5 x 10(-3) W/mK(2). This value is anomalously high for common transition-metal nitrides.

  • 5.
    Tholander, Christopher
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany.
    Zukauskaitè, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg, Germany.
    Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy2016Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 105, s. 199-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By combining theoretical prediction and experimental verification we investigate the piezoelectric properties of yttrium indium nitride (YxIn1-xN). Ab initio calculations show that the YxIn1-xN wurtzite phase is lowest in energy among relevant alloy structures for 0≤x≤0.5. Reactive magnetron sputter epitaxy was used to prepare thin films with Y content up to x=0.51. The composition dependence of the lattice parameters observed in the grown films is in agreement with that predicted by the theoretical calculations confirming the possibility to synthesize a wurtzite solid solution. An AlN buffer layer greatly improves the crystalline quality and surface morphology of subsequently grown YxIn1-xN films. The piezoelectric response in films with x=0.09 and x=0.14 is observed using piezoresponse force microscopy. Theoretical calculations of the piezoelectric properties predict YxIn1−xN to have comparable piezoelectric properties to ScxAl1-xN.

  • 6.
    Wingqvist, Gunilla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Zukauskaite, Agne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Increased electromechanical coupling in w-ScxAl1-xN2010Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, nr 11, s. 112902-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low dielectric losses along with minor increased dielectric constant (ε). Ellipsometry measurements of the high frequency ε showed good agreement with density function perturbation calculations. Our data show that kt2 will improve from 7% to 10% by alloying AlN with up to 20 mol % ScN.

     

  • 7.
    Zukauskaite, Agne
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nanoprobe Mechanical and Piezoelectric Characterization of ScxAl1-xN(0001) Thin Films2015Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 212, nr 3, s. 666-673Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoindentation with in-situ electrical characterization was used to characterize piezoelectric scandium aluminum nitride (ScxAl1-xN) thin films with Sc contents up to x=0.3. The films were prepared by reactive magnetron sputtering using Al2O3 substrates with TiN seed layer/bottom electrodes at a substrate temperature of 400 °C. X-ray diffraction shows c-axis oriented wurtzite ScxAl1-xN, where the crystal quality decreases with increasing x. Piezoresponse force microscopy in mapping mode shows a single piezoelectric polarization phase in all samples. The hardness and decreases from 17 GPa in AlN to 11 GPa in Sc0.3Al0.7N, while reduced elastic modulus decreases from 265 GPa to 224 GPa, respectively. Both direct and converse piezoelectric measurements are demonstrated by first applying the load and generating the voltage and later by applying the voltage and measuring film displacement using a conductive boron doped nanoindenter tip. The Sc0.2Al0.8N films exhibit an increase in generated voltage by 15% in comparison to AlN and a correspondingly larger displacement upon applied voltage, comparable to results obtained by double beam interferometry and piezoresponse force microscopy.

     

  • 8.
    Žukauskaitė, Agnė
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Metastable ScAlN and YAlN Thin Films Grown by Reactive Magnetron Sputter Epitaxy2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Metastable ScxAl1-xN and YxAl1-xN thin films were deposited in an ultra high vacuum system using reactive magnetron sputter epitaxy from elemental Al, Sc, and Y targets in Ar/N2 gas mixture. Their structural, electrical, optical, mechanical, and piezoelectrical properties were investigated by using the transmission electron microscopy, x-ray diffraction, spectroscopic ellipsometry, I-V and C-V measurements, nanoindentation, and two different techniques for piezoelectric characterization: piezoresponse force microscopy and double beam interferometry.

    Compared to AlN, improved electromechanical coupling and increase in piezoelectric response was found in ScxAl1-xN/TiN/Al2O3 structures with Sc content up to x=0.2. Decreasing the growth temperature down to 400 °C improved the microstructure and crystalline quality of the material. Microstructure of the films had a stronger influence on piezoelectric properties than the crystalline quality, which affected the leakage currents. When x was increased from x=0 to x=0.3, the hardness and reduced Young’s modulus Er showed a decrease from 17 GPa to 11 GPa, and 265 GPa down to 224 GPa, respectively. In ScxAl1-xN/InyAl1-yN superlattices, ScxAl1-xN layers negative lattice mismatched to In-rich InyAl1-yN were found to be stable at higher Sc concentration (x=0.4) than lattice-matched or positive lattice mismatched layers, confirmed by first principle (ab initio) calculations using density-functional formalism.

    Al-rich YxAl1-xN thin films were synthesized and reported for the first time. Formation of solid solution was observed up to x=0.22 and an increase in growth temperature up to 900°C improved the crystalline quality of the YxAl1-xN films. The band gap of YxAl1-xN decreased from 6.2 eV for AlN down to 4.5 eV (x=0.22) and was shown to follow Vegard’s rule. Refractive indices and extinction coefficients were also determined. Lattice constants of wurtzite YxAl1-xN measured experimentally are in good agreement with theoretical predictions obtained through ab initio calculations. The mixing enthalpy

    Delarbeid
    1. Increased electromechanical coupling in w-ScxAl1-xN
    Åpne denne publikasjonen i ny fane eller vindu >>Increased electromechanical coupling in w-ScxAl1-xN
    Vise andre…
    2010 (engelsk)Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, nr 11, s. 112902-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low dielectric losses along with minor increased dielectric constant (ε). Ellipsometry measurements of the high frequency ε showed good agreement with density function perturbation calculations. Our data show that kt2 will improve from 7% to 10% by alloying AlN with up to 20 mol % ScN.

     

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-59839 (URN)10.1063/1.3489939 (DOI)000282032900055 ()
    Merknad
    Original Publication: Gunilla Wingqvist, Ferenc Tasnadi, Agne Zukauskaite, Jens Birch, Hans Arwin and Lars Hultman, Increased electromechanical coupling in w-ScxAl1-xN, 2010, Applied Physics Letters, (97), 11, 112902. http://dx.doi.org/10.1063/1.3489939 Copyright: American Institute of Physics http://www.aip.org/ Tilgjengelig fra: 2010-09-27 Laget: 2010-09-27 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    2. Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films
    Vise andre…
    2012 (engelsk)Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, nr 9, s. 093527-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Piezoelectric wurtzite ScxAl1-xN (x=0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(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 °C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 °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 °C. The piezoelectric response of epitaxial ScxAl1-xN 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.

    sted, utgiver, år, opplag, sider
    American Institute of Physics (AIP), 2012
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-76471 (URN)10.1063/1.4714220 (DOI)000304109900044 ()
    Tilgjengelig fra: 2012-04-10 Laget: 2012-04-10 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    3. Nanoprobe Mechanical and Piezoelectric Characterization of ScxAl1-xN(0001) Thin Films
    Åpne denne publikasjonen i ny fane eller vindu >>Nanoprobe Mechanical and Piezoelectric Characterization of ScxAl1-xN(0001) Thin Films
    Vise andre…
    2015 (engelsk)Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 212, nr 3, s. 666-673Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Nanoindentation with in-situ electrical characterization was used to characterize piezoelectric scandium aluminum nitride (ScxAl1-xN) thin films with Sc contents up to x=0.3. The films were prepared by reactive magnetron sputtering using Al2O3 substrates with TiN seed layer/bottom electrodes at a substrate temperature of 400 °C. X-ray diffraction shows c-axis oriented wurtzite ScxAl1-xN, where the crystal quality decreases with increasing x. Piezoresponse force microscopy in mapping mode shows a single piezoelectric polarization phase in all samples. The hardness and decreases from 17 GPa in AlN to 11 GPa in Sc0.3Al0.7N, while reduced elastic modulus decreases from 265 GPa to 224 GPa, respectively. Both direct and converse piezoelectric measurements are demonstrated by first applying the load and generating the voltage and later by applying the voltage and measuring film displacement using a conductive boron doped nanoindenter tip. The Sc0.2Al0.8N films exhibit an increase in generated voltage by 15% in comparison to AlN and a correspondingly larger displacement upon applied voltage, comparable to results obtained by double beam interferometry and piezoresponse force microscopy.

     

    sted, utgiver, år, opplag, sider
    John Wiley & Sons, 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-103830 (URN)10.1002/pssa.201431634 (DOI)000351530800029 ()
    Merknad

    On the day of the defence date of the Ph.D. Thesis, the status of this article was Manuscript.

    Tilgjengelig fra: 2014-01-29 Laget: 2014-01-29 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    4. Stabilization of Wurtzite Sc0.4Al0.6N in Pseudomorphic Epitaxial ScxAl1-xN/InyAl1-yN Superlattices
    Åpne denne publikasjonen i ny fane eller vindu >>Stabilization of Wurtzite Sc0.4Al0.6N in Pseudomorphic Epitaxial ScxAl1-xN/InyAl1-yN Superlattices
    Vise andre…
    2015 (engelsk)Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 94, s. 101-110Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Pseudomorphic stabilization in wurtzite ScxAl1-xN/AlN and ScxAl1-xN/InyAl1-yN superlattices (x=0.2, 0.3, and 0.4; y=0.2-0.72), grown by reactive magnetron sputter epitaxy was investigated. X-ray diffraction and transmission electron microscopy show that in ScxAl1-xN/AlN superlattices the compressive biaxial stresses due to positive lattice mismatch in Sc0.3Al0.7N and Sc0.4Al0.6N lead to loss of epitaxy, although the structure remains layered. For the negative lattice mismatched In-rich ScxAl1-xN/InyAl1-yN superlattices a tensile biaxial stress promotes the stabilization of wurtzite ScxAl1-xN even for the highest investigated concentration x=0.4. Ab initio calculations with fixed in-plane lattice parameters show a reduction in mixing energy for wurtzite ScxAl1-xN under tensile stress when x≥0.375 and support the experimental results.

    sted, utgiver, år, opplag, sider
    Elsevier, 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-103831 (URN)10.1016/j.actamat.2015.04.033 (DOI)000357143500010 ()
    Tilgjengelig fra: 2014-01-29 Laget: 2014-01-29 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    5. YxAl1-xN Thin Films
    Åpne denne publikasjonen i ny fane eller vindu >>YxAl1-xN Thin Films
    Vise andre…
    2012 (engelsk)Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, nr 42, s. 422001-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Reactive magnetron sputtering was used to deposit YxAl1-xN thin films, 0≤x≤0.22, onto Al2O3(0001) and Si(100) substrates. X-ray diffraction and analytical electron microscopy show that the films are solid solutions. Lattice constants are increasing with Y concentration, in agreement with ab initio calculations. Spectroscopic ellipsometry measurements reveal a band gap decrease from 6.2 eV (x=0) down to 4.9 eV (x=0.22). Theoretical investigations within the special quasirandom structure approach show that the wurtzite structure has the lowest mixingenthalpy for 0≤x≤0.75.

    sted, utgiver, år, opplag, sider
    Institute of Physics Publishing (IOPP), 2012
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-76472 (URN)10.1088/0022-3727/45/42/422001 (DOI)000309766700001 ()
    Merknad

    funding agencies|Linkoping Linnaeus Initiative on Nanoscale Functional Materials (LiLiNFM)||Swedish Research Council (VR)|349-2008-6582|FCT Portugal|SFRH/BPD/66818/2009|VR|2010-3848|Swedish Governmental Agency for Innovation Systems (VINNOVA)|2011-03486|

    Tilgjengelig fra: 2012-04-10 Laget: 2012-04-10 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    6. Bandgap Engineering and Optical Constants of YxAl1-xN Alloys
    Åpne denne publikasjonen i ny fane eller vindu >>Bandgap Engineering and Optical Constants of YxAl1-xN Alloys
    Vise andre…
    2013 (engelsk)Inngår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 52, nr 8Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We study wurtzite Yx Al1-xN (0 andlt;= x andlt;= 0:22) films with (0001) orientation deposited by magnetron sputtering epitaxy on Si(100) substrates and we determine the alloys band gap energies and optical constants. Room temperature spectroscopic ellipsometry (SE) is employed in the energy range from 1 to 6.3 eV, and data modeling based on the standard dielectric function model is used. As a result of the SE data analysis the Yx Al1-xN refractive index and extinction coefficient are determined. The band gap of Yx Al1-xN is found to decrease linearly from 6.2 eV (x=0) down to 4.5 eV (x=0:22). We further observe an increase of the refractive index with increasing Y content; from 1.93 to 2.20 (at 2 eV) for x=0 and 0.22, respectively, reflecting the increase in material density.

    sted, utgiver, år, opplag, sider
    Japan Society of Applied Physics, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-98153 (URN)10.7567/JJAP.52.08JM02 (DOI)000323883100159 ()
    Merknad

    Funding Agencies|FCT|REF:SFRH/BPD/66818/2009|Swedish Research Council (VR)|2010-3848|Linko "ping Linnaeus Initiative on Nanoscale Functional Materials (LiLiNFM)||Swedish Governmental Agency for Innovation Systems (VINNOVA)|2011-03486|

    Tilgjengelig fra: 2013-09-30 Laget: 2013-09-30 Sist oppdatert: 2017-12-06
  • 9.
    Žukauskaitė, Agnė
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Metastable YAlN and ScAlN thin films: growth and characterization2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    ScxAl1-xN and YxAl1-xN thin films were deposited in a ultra high vacuum system using reactive magnetron co-sputtering from elemental Al, Sc and Y targets in Ar/N2. Their mechanical, electrical, optical, and piezoelectrical properties were investigated with the help of transmission electron microscopy, xray diffraction, ellipsometry, I-V and C-V measurements, and two different techniques for piezoelectric characterization: piezoresponse force microscopy and double beam interferometry. Compared to AlN, improved electromechanical coupling and increase in piezoelectric response was found in ScxAl1-xN/TiN/Al2O3 structures with Sc content up to x=0.2. Microstructure of the films had a stronger influence on piezoelectric properties than the crystalline quality, which affected the leakage currents. YxAl1-xN thin films show a formation of solid solution up to x=0.22. Lattice constants obtained experimentally are in good agreement with theoretical predictions obtained through first principle (ab initio) calculations using density-functional formalism. The mixing enthalpy for wurtzite, cubic, and layered hexagonal phases of the YxAl1-xN system was also calculated.

    Delarbeid
    1. Increased electromechanical coupling in w-ScxAl1-xN
    Åpne denne publikasjonen i ny fane eller vindu >>Increased electromechanical coupling in w-ScxAl1-xN
    Vise andre…
    2010 (engelsk)Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, nr 11, s. 112902-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low dielectric losses along with minor increased dielectric constant (ε). Ellipsometry measurements of the high frequency ε showed good agreement with density function perturbation calculations. Our data show that kt2 will improve from 7% to 10% by alloying AlN with up to 20 mol % ScN.

     

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-59839 (URN)10.1063/1.3489939 (DOI)000282032900055 ()
    Merknad
    Original Publication: Gunilla Wingqvist, Ferenc Tasnadi, Agne Zukauskaite, Jens Birch, Hans Arwin and Lars Hultman, Increased electromechanical coupling in w-ScxAl1-xN, 2010, Applied Physics Letters, (97), 11, 112902. http://dx.doi.org/10.1063/1.3489939 Copyright: American Institute of Physics http://www.aip.org/ Tilgjengelig fra: 2010-09-27 Laget: 2010-09-27 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    2. Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films
    Vise andre…
    2012 (engelsk)Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, nr 9, s. 093527-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Piezoelectric wurtzite ScxAl1-xN (x=0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(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 °C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 °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 °C. The piezoelectric response of epitaxial ScxAl1-xN 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.

    sted, utgiver, år, opplag, sider
    American Institute of Physics (AIP), 2012
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-76471 (URN)10.1063/1.4714220 (DOI)000304109900044 ()
    Tilgjengelig fra: 2012-04-10 Laget: 2012-04-10 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    3. YxAl1-xN Thin Films
    Åpne denne publikasjonen i ny fane eller vindu >>YxAl1-xN Thin Films
    Vise andre…
    2012 (engelsk)Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, nr 42, s. 422001-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Reactive magnetron sputtering was used to deposit YxAl1-xN thin films, 0≤x≤0.22, onto Al2O3(0001) and Si(100) substrates. X-ray diffraction and analytical electron microscopy show that the films are solid solutions. Lattice constants are increasing with Y concentration, in agreement with ab initio calculations. Spectroscopic ellipsometry measurements reveal a band gap decrease from 6.2 eV (x=0) down to 4.9 eV (x=0.22). Theoretical investigations within the special quasirandom structure approach show that the wurtzite structure has the lowest mixingenthalpy for 0≤x≤0.75.

    sted, utgiver, år, opplag, sider
    Institute of Physics Publishing (IOPP), 2012
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-76472 (URN)10.1088/0022-3727/45/42/422001 (DOI)000309766700001 ()
    Merknad

    funding agencies|Linkoping Linnaeus Initiative on Nanoscale Functional Materials (LiLiNFM)||Swedish Research Council (VR)|349-2008-6582|FCT Portugal|SFRH/BPD/66818/2009|VR|2010-3848|Swedish Governmental Agency for Innovation Systems (VINNOVA)|2011-03486|

    Tilgjengelig fra: 2012-04-10 Laget: 2012-04-10 Sist oppdatert: 2017-12-07bibliografisk kontrollert
  • 10.
    Žukauskaitė, Agnė
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tholander, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Pališaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ben Sedrine, Nebiha
    Instituto Tecnológico e Nuclear, 2686-953 Sacavém and CFNUL, Lisbon 1649-003, Portugal.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    YxAl1-xN Thin Films2012Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, nr 42, s. 422001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reactive magnetron sputtering was used to deposit YxAl1-xN thin films, 0≤x≤0.22, onto Al2O3(0001) and Si(100) substrates. X-ray diffraction and analytical electron microscopy show that the films are solid solutions. Lattice constants are increasing with Y concentration, in agreement with ab initio calculations. Spectroscopic ellipsometry measurements reveal a band gap decrease from 6.2 eV (x=0) down to 4.9 eV (x=0.22). Theoretical investigations within the special quasirandom structure approach show that the wurtzite structure has the lowest mixingenthalpy for 0≤x≤0.75.

  • 11.
    Žukauskaitė, Agnė
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. Fraunhofer Institute for Applied Solid State Physics, Freiburg, Germany.
    Tholander, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Pališaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Stabilization of Wurtzite Sc0.4Al0.6N in Pseudomorphic Epitaxial ScxAl1-xN/InyAl1-yN Superlattices2015Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 94, s. 101-110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pseudomorphic stabilization in wurtzite ScxAl1-xN/AlN and ScxAl1-xN/InyAl1-yN superlattices (x=0.2, 0.3, and 0.4; y=0.2-0.72), grown by reactive magnetron sputter epitaxy was investigated. X-ray diffraction and transmission electron microscopy show that in ScxAl1-xN/AlN superlattices the compressive biaxial stresses due to positive lattice mismatch in Sc0.3Al0.7N and Sc0.4Al0.6N lead to loss of epitaxy, although the structure remains layered. For the negative lattice mismatched In-rich ScxAl1-xN/InyAl1-yN superlattices a tensile biaxial stress promotes the stabilization of wurtzite ScxAl1-xN even for the highest investigated concentration x=0.4. Ab initio calculations with fixed in-plane lattice parameters show a reduction in mixing energy for wurtzite ScxAl1-xN under tensile stress when x≥0.375 and support the experimental results.

  • 12.
    Žukauskaitė, Agnė
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Wingqvist, Gunilla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Pališaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Matloub, Ramin
    Ceramics Laboratory, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, SwitzerlandNational Laboratory, Oak Ridge, TN 37831, United States.
    Muralt, Paul
    Ceramics Laboratory, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland.
    Kim, Yunseok
    Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films2012Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, nr 9, s. 093527-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Piezoelectric wurtzite ScxAl1-xN (x=0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(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 °C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 °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 °C. The piezoelectric response of epitaxial ScxAl1-xN 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.

1 - 12 of 12
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