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BETA
Sandström, Pär
Alternative names
Publications (10 of 13) Show all publications
Tholander, C., Birch, J., Tasnádi, F., Hultman, L., Palisaitis, J., Persson, P. O., . . . Zukauskaitè, A. (2016). Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy. Acta Materialia, 105, 199-206
Open this publication in new window or tab >>Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy
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2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 105, p. 199-206Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
YInN, Thin films, Sputter deposition, Piezoelectricity, Ab initio calculations
National Category
Condensed Matter Physics Materials Chemistry Inorganic Chemistry Other Materials Engineering Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-125918 (URN)10.1016/j.actamat.2015.11.050 (DOI)000370086500023 ()
Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2017-11-30Bibliographically approved
Hsiao, C.-L., Magnusson, R., Palisaitis, J., Sandström, P., Persson, P. O. Å., Valyukh, S., . . . Birch, J. (2015). Curved-Lattice Epitaxial Growth of InxAl1-xN Nanospirals with Tailored Chirality. Nano letters (Print), 15(1), 294-300
Open this publication in new window or tab >>Curved-Lattice Epitaxial Growth of InxAl1-xN Nanospirals with Tailored Chirality
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2015 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 1, p. 294-300Article in journal (Refereed) Published
Abstract [en]

Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth (CLEG) of uniform coatings of single-crystalline InxAl1-xN nanospirals. The nanospirals are formed by sequentially stacking segments of curved nanorods on top of each other, where each segment is incrementally rotated around the spiral axis. By controlling the growth rate, segment length, rotation direction, and incremental rotation angle, spirals are tailored to predetermined handedness, pitch, and height.  The curved morphology of the segments is a result of a lateral compositional gradient across the segments while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties as well. Left- and right-handed nanospirals, tailored with 5 periods of 200 nm pitch, as confirmed by scanning electron microscopy, exhibit uniform spiral diameters of ~80 nm (local segment diameters of ~60 nm) with tapered hexagonal tips.  High resolution electron microscopy, in combination with nanoprobe energy dispersive X-ray spectroscopy and valence electron energy loss spectroscopy, show that individual nanospirals consist of an In-rich core with ~15 nm-diameter hexagonal cross-section, comprised of curved basal planes. The core is surrounded by an Al-rich shell with a thickness asymmetry spiraling along the core. The ensemble nanospirals, across the 1 cm2 wafers, show high in-plane ordering with respect to shape, crystalline orientation, and direction of compositional gradient. Mueller matrix spectroscopic ellipsometry shows that the tailored chirality is manifested in the polarization state of light reflected off the CLEG nanospiral-coated wafers. In that, the polarization state is shown to be dependent on the handedness of the nanospirals and the wavelength of the incident light in the ultraviolet-visible region.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015
Keywords
InAlN, nanospirals, chirality, sputtering, CLEG, GLAD, STEM, VEELS
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112512 (URN)10.1021/nl503564k (DOI)000348086100047 ()25427233 (PubMedID)
Projects
Growth of Metastable Ternary Group III-Nitride Semiconductor Nanostructures by unique design concepts and doping
Funder
Swedish Research Council, 621-2012-4420
Available from: 2014-12-01 Created: 2014-12-01 Last updated: 2018-03-08
Magnusson, R., Birch, J., Hsiao, C.-L., Sandström, P., Arwin, H. & Järrendahl, K. (2015). InxAl1-xN chiral nanorods mimicking the polarization features of scarab beetles. In: Akhlesh Lakhtakia, Mato Knez, Raúl Martín-Palma (Ed.), SPIE Proceedings Vol. 942: Bioinspiration, Biomimetics, and Bioreplication 2015. Paper presented at SPIE: smart structures NDE Bioinspiration, Biomimetics, and Bioreplication 2015 (pp. 94290A-1-94290A-8). SPIE - International Society for Optical Engineering, 9429
Open this publication in new window or tab >>InxAl1-xN chiral nanorods mimicking the polarization features of scarab beetles
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2015 (English)In: SPIE Proceedings Vol. 942: Bioinspiration, Biomimetics, and Bioreplication 2015 / [ed] Akhlesh Lakhtakia, Mato Knez, Raúl Martín-Palma, SPIE - International Society for Optical Engineering, 2015, Vol. 9429, p. 94290A-1-94290A-8Conference paper, Published paper (Refereed)
Abstract [en]

The scarab beetle Cetonia aurata is known to reflect light with brilliant colors and a high degree of circular polarization. Both color and polarization effects originate from the beetles exoskeleton and have been attributed to a Bragg reflection of the incident light due to a twisted laminar structure. Our strategy for mimicking the optical properties of the Cetonia aurata was therefore to design and fabricate transparent, chiral films. A series of films with tailored transparent structures of helicoidal InxAl1-xN nanorods were grown on sapphire substrates using UHV magnetron sputtering. The value of x is tailored to gradually decrease from one side to the other in each nanorod normal to its growth direction. This introduces an in-plane anisotropy with different refractive indices in the direction of the gradient and perpendicular to it. By rotating the sample during film growth the in-plane optical axis will be rotated from bottom to top and thereby creating a chiral film. Based on Muellermatrix ellipsometry, optical modeling has been done suggesting that both the exoskeleton of Cetonia aurata and our artificial material can be modeled by an anisotropic film made up of a stack of thin layers, each one with its in-plane optical axis slightly rotated with respect to the previous layer. Simulations based on the optical modeling were used to investigate how pitch and thickness of the film together with the optical properties of the constitutive materials affects the width and spectral position of the Bragg reflection band.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2015
Series
Proceedings of SPIE, ISSN 0277-786X ; 9429
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-119058 (URN)10.1117/12.2084164 (DOI)000357257400003 ()978-1-62841-532-2 (ISBN)
Conference
SPIE: smart structures NDE Bioinspiration, Biomimetics, and Bioreplication 2015
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2015-06-08 Created: 2015-06-08 Last updated: 2018-03-08Bibliographically approved
Zukauskaite, A., Broitman, E., Sandström, P., Hultman, L. & Birch, J. (2015). Nanoprobe Mechanical and Piezoelectric Characterization of ScxAl1-xN(0001) Thin Films. Physica Status Solidi (a) applications and materials science, 212(3), 666-673
Open this publication in new window or tab >>Nanoprobe Mechanical and Piezoelectric Characterization of ScxAl1-xN(0001) Thin Films
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2015 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 212, no 3, p. 666-673Article in journal (Refereed) 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.

 

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-103830 (URN)10.1002/pssa.201431634 (DOI)000351530800029 ()
Note

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

Available from: 2014-01-29 Created: 2014-01-29 Last updated: 2017-12-06Bibliographically approved
Magnusson, R., Birch, J., Sandström, P., Hsiao, C.-L., Arwin, H. & Järrendahl, K. (2014). Optical Mueller Matrix Modeling of Chiral AlxIn1-xN Nanospirals. Thin Solid Films, 571, 447-452
Open this publication in new window or tab >>Optical Mueller Matrix Modeling of Chiral AlxIn1-xN Nanospirals
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2014 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, p. 447-452Article in journal (Refereed) Published
Abstract [en]

Metamaterials in the form of chiral nanostructures have shown great potential for applications such as chemical and biochemical sensors and broadband or wavelength tunable circular polarizers. Here we demonstrate a method to produce tailored transparent chiral nanostructures with the wide-bandgap semiconductor AlxIn1 − xN. A series of anisotropic and transparent films of AlxIn1 − xN were produced using curved-lattice epitaxial growth on metallic buffer layers. By controlling the sample orientation during dual magnetron sputter deposition, nanospirals with right-handed or left-handed chirality were produced. Using a dual rotating compensator ellipsometer in reflection mode, the full Mueller matrix was measured in the spectral range 245–1700 nm at multiple angles of incidence. The samples were rotated one full turn around their normal during measurements to provide a complete description of the polarization properties in all directions. For certain wavelengths, unpolarized light reflected off these films becomes highly polarized with a polarization state close to circular. Nanostructured films with right- and left-handed chirality produce reflections with right- and left-handed near-circularly polarized light, respectively. A model with a biaxial layer in which the optical axes are rotated from bottom to top was fitted to the Mueller-matrix data. Hence we can perform non-destructive structural analysis of the complex thin layers and confirm the tailored structure. In addition, the refractive index, modeled with a biaxial Cauchy dispersion model, is obtained for the AlxIn1 − xN films.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Chiral nanostructures; Mueller matrix spectroscopic ellipsometry; Anisotropy; Optical modeling;High degree of circular polarization
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-106421 (URN)10.1016/j.tsf.2014.02.015 (DOI)000346055200020 ()
Available from: 2014-05-07 Created: 2014-05-07 Last updated: 2018-03-08
Muhammad, J., Sandström, P., Palisaitis, J., Darakchieva, V., Hsiao, C.-L., Persson, P., . . . Birch, J. (2014). Stress Evolution during Growth of GaN (0001)/Al2O3 (0001) by Reactive DC Magnetron Sputter Epitaxy. Journal of Physics D: Applied Physics, 47(14), 145301
Open this publication in new window or tab >>Stress Evolution during Growth of GaN (0001)/Al2O3 (0001) by Reactive DC Magnetron Sputter Epitaxy
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2014 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 47, no 14, p. 145301-Article in journal (Refereed) Published
Abstract [en]

We study the real time stress evolution, by in-situ curvature measurements, during magnetron sputter epitaxy of GaN (0001) epilayers at different growth temperatures, directly on Al2O3 (0001) substrates. The epilayers are grown by sputtering from a liquid Ga target in a mixed N2/Ar discharge. For 600 °C, a tensile biaxial stress evolution is observed, while for 700 °C and 800 °C, compressive stress evolutions are observed. Structural characterization by crosssectional transmission electron microscopy, and atomic force microscopy revealed that films grew at 700 °C and 800 °C in a layer-by-layer mode while a growth temperature of 600 °C led to an island growth mode. High resolution Xray diffraction data showed that edge and screw threading dislocation densities decreased with increasing growth temperature with a total density of 5.5×1010 cm-2. The observed stress evolution and growth modes are explained by a high adatom mobility during magnetron sputter epitaxy at 700 - 800 °C. Also other possible reasons for the different stress evolutions are discussed.

Keywords
GaN, Magnetron Sputter Epitaxy, Stress and Strain, Sputtering, XRD
National Category
Natural Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-84652 (URN)10.1088/0022-3727/47/14/145301 (DOI)000333332600007 ()2-s2.0-84896955140 (Scopus ID)
Available from: 2012-10-16 Created: 2012-10-16 Last updated: 2018-03-08Bibliographically approved
Hsiao, C.-L., Magnusson, R., Palisaitis, J., Sandström, P., Valyukh, S., Persson, P., . . . Birch, J. (2012). Curved-lattice epitaxial growth of chiral AlInN twisted nanorods for optical applications.
Open this publication in new window or tab >>Curved-lattice epitaxial growth of chiral AlInN twisted nanorods for optical applications
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2012 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Despite of using chiral metamaterials to manipulate light polarization states has been demonstrated their great potential for applications such as invisible cloaks, broadband or wavelength-tunable circular polarizers, microreflectors, etc. in the past decade [1-6], operating wavelength in ultraviolet-visible range is still a challenge issue. Since these chiral structures often consist of metallic materials, their operation is designed for the infrared and microwave regions [2-4]. Here, we show how a controlled curved-lattice epitaxial growth (CLEG) of wide-bandgap AlInN semiconductor curved nanocrystals [7] can be exploited as a novel route for tailoring chiral nanostructures in the form of twisted nanorods (TNRs). The fabricated TNRs are shown to reflect light with a high degree of polarization as well as a high degree of circular polarization (that is, nearly circularly polarized light) in the ultravioletvisible region. The obtained polarization is shown to be dependent on the handedness of the TNRs.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-85902 (URN)
Available from: 2012-12-03 Created: 2012-12-03 Last updated: 2018-03-08Bibliographically approved
Järrendahl, K., Birch, J., Magnusson, R., Hsiao, C.-L., Sandström, P., Berlind, T., . . . Arwin, H. (2012). Polarization of Light Reflected from Chiral Structures - Calculations Compared with Mueller Matrix Ellipsometry Measurements on Natural and Synthetic Samples. Paper presented at 7th Workshop Ellipsometry, Leipzig, March 5-7, 2012.
Open this publication in new window or tab >>Polarization of Light Reflected from Chiral Structures - Calculations Compared with Mueller Matrix Ellipsometry Measurements on Natural and Synthetic Samples
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2012 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

The Mueller matrix elements mij representing the polarization response from a nanostructured materialis determined by the constituent materials optical properties and the superstructure. Here, we investigate how chiral structures in form of helicoidally stacked uniaxial layers determine mij as a functionof polarization state, wavelength, incidence angle and azimuthal angle of the incoming light. The studied parameters include the layer materials ordinary/extraordinary optical properties, Euler angle values, and layer thickness as well as the thickness and pitch of the helicoidal superstructure. Sub- and superstructure inhomogeneity is also introduced. From the Fresnel-based calculations, mij aswell as the degree of polarization, ellipticity and azimuth of the polarization ellipse are obtained and presented as contour and trace plots to give a complete view of the polarization behavior. The results from the calculations are compared with Mueller matrix spectroscopic ellipsometry measurements of both natural and synthesized helicoidal structures. The measurements were performed with a dualrotating compensator system (RC2, J.A. Woollam Co., Inc.) for wavelengths in the range from 245 to 1000 nm and incident angles from 20 to 75°. For some measurements the azimuthal angle of the incident light was varied. The investigated natural chiral structures were exoskeletons from several beetles in the scarab subfamilies Cetoniinae and Rutelinae. As predicted from the calculations it isobserved that the reflection from these beetles can have a high degree of polarization and high ellipticity (near-circular polarization). Both left- and right-polarization was observed. The synthesized structures are helicoidal nanorods of Al1−xInxN grown on sapphire substrates with metal-nitride seedlayers using UHV magnetron sputtering. Due to an internal composition gradient (a variation of x) in the crystalline structure, the nanorods will tilt away from the substrate normal. Helicoidal structures can thus be obtained by rotating the substrate around its normal during deposition. Samples with different pitch and layer thickness with right-handed as well as left-handed chirality were grown. Also for these structures both left and right near-circular polarized light is observed. By combining calculations, ellipsometry measurements and scanning electron microscopy characterization we get agood input to build layered models of the natural and synthetic samples. After regression fitting agood agreement between calculated and measured optical data were obtained.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-86008 (URN)
Conference
7th Workshop Ellipsometry, Leipzig, March 5-7, 2012
Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2018-03-08
Hsiao, C.-L., Palisaitis, J., Junaid, M., Chen, R.-S., Persson, P. O. .., Sandström, P., . . . Birch, J. (2011). Composition tunable Al1-xInxN nanorod arrays grown by ultra-high-vacuum magnetron sputter epitaxy. , 5(2)
Open this publication in new window or tab >>Composition tunable Al1-xInxN nanorod arrays grown by ultra-high-vacuum magnetron sputter epitaxy
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2011 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Self-assembled ternary Al1-xInxN nanorod arrays with variable In concentration, 0.10 ≤ x ≤ 0.32 have been realized onto c-plane sapphire substrates by ultra-high-vacuum magnetron sputter epitaxy with Ti0.21Zr0.79N or VN seed layers assistance. The formation of nanorods was very sensitive to the applied seed layer. Without proper seed layer assistance a continuous Al1-xInxN film was grown. The nanorods exhibit hexagonal crosssections with preferential growth along the c axis. A coaxial rod structure with higher In concentration in the core was observed by (scanning) transmission electron microscopy in combination with low-loss electron energy loss spectroscopy and energy dispersive xray spectroscopy. 5 K cathodoluminescence spectroscopy of Al0.86In0.14N nanorods revealed band edge emission at ~5.46 eV, which was accompanied by a strong defectrelated emission at ~ 3.38 eV.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-67983 (URN)
Available from: 2011-05-04 Created: 2011-05-04 Last updated: 2018-03-08Bibliographically approved
Hsiao, C.-L., Palisaitis, J., Muhammad, J., Chen, R.-S., Persson, P., Sandström, P., . . . Birch, J. (2011). Spontaneous Formation of AlInN Core–Shell Nanorod Arrays by Ultrahigh-Vacuum Magnetron Sputter Epitaxy. Applied Physics Express, 4(115002)
Open this publication in new window or tab >>Spontaneous Formation of AlInN Core–Shell Nanorod Arrays by Ultrahigh-Vacuum Magnetron Sputter Epitaxy
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2011 (English)In: Applied Physics Express, ISSN 1882-0786, Vol. 4, no 115002Article in journal (Refereed) Published
Abstract [en]

The spontaneous formation of AlInN core–shell nanorod arrays with variable In concentration has been realized by ultrahigh-vacuum magnetron sputter epitaxy with Ti0.21Zr0.79N or VN seed layer assistance. The nanorods exhibit hexagonal cross sections with preferential growth along the c-axis. A core–shell rod structure with a higher In concentration in the core was observed by (scanning) transmission electron microscopy in combination with low-loss electron energy loss spectroscopy and energy dispersive X-ray spectroscopy. 5 K cathodoluminescence spectroscopy of Al0.86In0.14N nanorods revealed band edge emission at ∼5.46 eV, which was accompanied by a strong defect-related emission at ∼3.38 eV

Place, publisher, year, edition, pages
Japan Society of Applied Physics, 2011
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-73161 (URN)10.1143/APEX.4.115002 (DOI)000298289700028 ()
Note
Funding agencies|Swedish Strategic Foundation (SSF)||Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2018-03-08
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