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  • 1.
    Granqvist, C.-G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bayrak Pehlivan, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, S. V.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lansåker, Pia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Oxide-based electrochromics: Advances in materials and devices2011In: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 1328, p. 11-22Article in journal (Refereed)
  • 2.
    Granqvist, C.-G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, S. V.
    Li, S.-Y.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, N. R.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Progress in chromogenic materials and devices: New data on thermochromic VO2-based materials and on electrochromic nickel-tungsten-oxide films2010In: Book of Abstracts: Functional Materials and Nanotechnologies 2010, 2010, p. 24-Conference paper (Refereed)
  • 3.
    Granqvist, C.-G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, S. V.
    Li, S.-Y.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, N. R.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Avendano, E.
    Chromogenics for sustainable energy: Some advances in thermochromics and electrochromics2010In: International Journal of Advances in Science and Technology, ISSN 2229-5216, Vol. 75, p. 55-64Article in journal (Refereed)
    Abstract [en]

    ABSTRACT: Chromogenic materials are able to change their optical properties in response to external stimuli such as temperature (in thermochromic materials) and electrical charge insertion (in electrochromic materials). Below we review some recent advances for these types of materials. Specifically we first discuss the limitations of thermochromic VO2 films for energy efficient fenestration and show from calculations that nanocomposites containing VO2 can have superior properties and display high luminous transmittance and large temperature-dependent solar transmittance modulation. Even better results may be found for nanoparticles of VO2:Mg. In the second part of the paper we survey some recent progress for electrochromic devices and show that W oxide films have increased coloration efficiency when some Ni oxide is added. We also present initial results for flexible electrochromic foils produced by roll-to-roll coating and continuous lamination.

    Article · Oct 2010 · Advances in Science and Technology

  • 4.
    Granqvist, Claes Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Jonsson, E K
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Marsal, Roser
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Roos, Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Topalian, Zareh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Azens, A
    Georen, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gustavsson, G
    Karmhag, R
    Smulko, J
    Kish, L B
    Electrochromic foil-based devices: Optical transmittance and modulation range, effect of ultravioled irradiation, and quality assessment by 1/f current noise2008In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, no 17, p. 5921-5926Article in journal (Refereed)
    Abstract [en]

    We introduce electrochromic (EC) technology for modulating the transmittance of visible light and solar radiation in window apertures, with focus on recent work on foil-type devices embodying sputter deposited WO3 and NiO films joined by a polymer electrolyte. The purpose of this paper is to present a number of new and preliminary results showing that (i) double-sided antireflection coatings based on dip coating can enhance the transmittance significantly, (ii) tandem foils can yield a ratio between bleached-state and colored-state transmittance exceeding fifty, (iii) solar irradiance onto the EC device can enhance its charge insertion dynamics and thereby its optical modulation, and (iv) electromagnetic noise spectroscopy may serve as quality assessment of EC devices.

  • 5.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lansåker, Pia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Oxide-based electrochromics: Advances in materials and devices.2011In: Materials Research Society Symposium Proceedings, vol. 1328, Materials Research Society, 2011, p. 11-22Conference paper (Refereed)
  • 6.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Progress in chromogenic materials and devices: New data on thermochromic VO2-based materials and electrochromic nickel-tungsten-oxide films2010In: In Book of Abstracts: Functional Materials and Nanotechnologies 2010, University of Latvia, Riga, March 16-19, 2010, 2010, p. 24-Conference paper (Refereed)
  • 7.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Progress in Chromogenic Materials and Devices: New Data on Thermochromic Vanadium-Oxide-Based Materials and on Electrochromic Nickel-Tungsten-Oxide Based Foils2010Conference paper (Refereed)
  • 8.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Avendaño, Esteban
    Chromogenics for Sustainable Energy: Some Advances in Thermochromics and Electrochromics2010In: Advances in Science and Technology, ISSN 1662-0356, Vol. 75, p. 55-64Article in journal (Refereed)
    Abstract [en]

    Chromogenic materials are able to change their optical properties in response to external stimuli such as temperature (in thermochromic materials) and electrical charge insertion (in electrochromic materials). Below we review some recent advances for these types of materials. Specifically we first discuss the limitations of thermochromic VO2 films for energy efficient fenestration and show from calculations that nanocomposites containing VO2 can have superior properties and display high luminous transmittance and large temperature-dependent solar transmittance modulation. Even better results may be found for nanoparticles of VO2:Mg. In the second part of the paper we survey some recent progress for electrochromic devices and show that W oxide films have increased coloration efficiency when some Ni oxide is added. We also present initial results for flexible electrochromic foils produced by roll-to-roll coating and continuous lamination.

  • 9.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru R.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    von Kraemer, S.
    Georén, P.
    Advances in chromogenic materials and devices2010In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, no 11, p. 3046-3053Article in journal (Refereed)
    Abstract [en]

    Chromogenic materials allow the transmittance of visible light and solar energy to be varied under the action of an external stimulus This paper first discusses buildings related energy savings that can be accomplished by chromogenic technologies, and their beneficial effects on comfort issues We then summarize recent work on thermochromic VO2-based thin films with particular attention to multi-layers of VO2 and TiO2 and to new VO2 Mg films for which the doping gives significantly lowered absorption of visible light The final part covers electrochromic materials and devices with foci on coloration efficiency and on durability issues for foil-type constructions based on films of WO3 and NiO.

  • 10.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    von Kræmer, S.
    Georén, P.
    Advances in chromogenic materials and devices2009In: Proceedings of 6th International Symposium on Transparent Oxide Thin Films for Electronics and Optics, April 15-17, 2009, Tokyo Fashin Town Building, Japan, 2009, p. 27-36Conference paper (Refereed)
  • 11.
    Green, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Mixed Nickel Tungsten Oxide2009Conference paper (Refereed)
  • 12.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromic Nickel – Tungsten Oxides: Optical, Electrochemical and Structural Characterization of Sputter-deposited Thin Films in the Whole Composition Range2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates the electrochromic NixW1-x oxide thin film system, where 0 < x < 1. The thin films were deposited by reactive DC magnetron co-sputtering from one Ni and one W metal target. In addition, Ni oxide was deposited with water vapor added to the sputtering gas. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron-, Rutherford backscattering- and Raman spectroscopy. Possible nanostructures were studied by ellipsometry together with effective medium theory. Optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in 1 M lithium perchlorate in propylene carbonate (Li-PC). Li-PC electrolyte was used as it is being compatible with both W and Ni oxides. Few studies have previously been made on Ni oxides in Li-PC.

    Films with high Ni content, 0.85 < x < 1, were polycrystalline and all other films were amorphous. W-rich films, x < 0.5, consisted of a mixture of W oxide and NiWO4 -phases, and the Ni-rich samples, x > 0.5, probably consisted of hydrated Ni oxide and NiWO4 -phases. Films with 0 < x < 0.3 showed electrochromic properties similar to W oxide, and films with 0.7 < x < 1 behaved as Ni oxide. For 0.4 < x < 0.7 no optical change was seen. At the border of cathodic electrochromic and non-electrochromic behavior, i.e. x ~ 0.4, the sample behaved as an optically passive intercalation material. The transmittance change was 0.45 and 0.15 for the W-rich and Ni-rich films, respectively. Ni addition to W oxide improved the coloration efficiency. For the Ni-rich films the charge insertion/extraction and optical modulation was low and an aging effect resulted in strong bleaching of the samples. The advantage of W addition to Ni oxide was that the transparency at the bleached state was enhanced. Moreover, it was found that the hydrous character of the Ni oxide had a large impact on the electrochromic performance, both when electrochemically cycled in KOH and in the non-aqueous Li-PC.

    List of papers
    1. Electrochromism in Nickel Oxide and Tungsten Oxide Thin Films: Ion Intercalation from Different Electrolytes
    Open this publication in new window or tab >>Electrochromism in Nickel Oxide and Tungsten Oxide Thin Films: Ion Intercalation from Different Electrolytes
    Show others...
    2009 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 93, no 12, p. 2050-2055Article in journal (Refereed) Published
    Abstract [en]

    Electrochromic (EC) NiOz and WOy thin films were prepared by sputtering   and were used in a feasibility study aimed at investigating mixtures of   these two oxides. The object was to identify a suitable electrolyte,   compatible with both NiOz and WOy. To that end we carried out cyclic   voltammetry (CV) in potassium hydroxide (KOH), propionic acid, and   lithium perchlorate in propylene carbonate (Li-PC). WOy could be   coloured in propionic acid and Li-PC, while NiOz could be coloured only   in KOH. Both films showed best stability in Li-PC, which hence is well   suited for further studies of mixed NiOz and WOy.

    Keywords
    Electrochromism, Nickel oxide, Tungsten oxide, Cyclic voltammetry, Spectrophotometry
    National Category
    Physical Sciences Engineering and Technology
    Research subject
    Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-122131 (URN)10.1016/j.solmat.2009.05.009 (DOI)000271792200005 ()
    Available from: 2011-09-21 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
    2. Structure and composition of sputter-deposited nickel-tungsten oxide films
    Open this publication in new window or tab >>Structure and composition of sputter-deposited nickel-tungsten oxide films
    Show others...
    2011 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 7, p. 2062-2066Article in journal (Refereed) Published
    Abstract [en]

    Films of mixed nickel-tungsten oxide, denoted NixW1−x oxide, were prepared by reactive DC magnetron cosputtering from metallic targets and were characterized by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x<0.50 the films comprised a mixture of amorphous WO3 and nanosized NiWO4, at x=0.50 the nanosized NiWO4 phase was dominating, and at x>0.50 the films contained nanosized NiO and NiWO4.

    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-178364 (URN)10.1016/j.tsf.2010.10.033 (DOI)
    Available from: 2012-07-31 Created: 2012-07-31 Last updated: 2017-12-07Bibliographically approved
    3. Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory
    Open this publication in new window or tab >>Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory
    Show others...
    2012 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 4, p. 044308-Article in journal (Refereed) Published
    Abstract [en]

    Films of NixW1−x oxide with 0.05 ≤ x ≤ 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract accurate data on the dielectric function in the photon range 0.062 to 5.62 eV. The results for 0.62 to 5.62 eV were compared with computations from the Bruggeman effective medium theory applied to two nanostructural models: one representing a random mixture of structural entities characterized by the dielectric functions of WO3 and NiWO4 and the other describing a random mixture of WO3 and NiO. Unambiguous evidence was found in favor of the former model, and hence the films are composed of nanosized tungsten oxide and nickel tungstate. This agrees excellently with an earlier investigation of ours on NixW1−x oxide films, where nanostructure was inferred from Raman spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction.

    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-179762 (URN)10.1063/1.4748166 (DOI)000308410100079 ()
    Available from: 2012-08-22 Created: 2012-08-22 Last updated: 2017-12-07Bibliographically approved
    4. Electrochromism in sputter deposited nickel-containing tungsten oxide films
    Open this publication in new window or tab >>Electrochromism in sputter deposited nickel-containing tungsten oxide films
    2012 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 99, p. 339-344Article in journal (Refereed) Published
    Abstract [en]

    Thin films of NixW1-x oxide were prepared by reactive DC magnetron co-sputtering and were investigated by optical and electrochemical measurements. Electrochromism was found only for 0<x<0.3 but not for 0.3<x<0.6, though films with x~0.4 could still sustain reversible charge insertion. The coloration efficiency was largest for 0.10<x<0.15. The charge capacity of the NixW1-x oxide films decreased upon increasing the value of x as a consequence of a decreasing ion diffusion coefficient leading to slower kinetics.

    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-178580 (URN)10.1016/j.solmat.2011.12.025 (DOI)000301167200048 ()
    Funder
    Swedish Research CouncilEU, FP7, Seventh Framework Programme, 211948Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning
    Available from: 2012-07-31 Created: 2012-07-31 Last updated: 2017-12-07Bibliographically approved
    5. Structure and optical properties of electrochromic tungsten-containing nickel oxide films
    Open this publication in new window or tab >>Structure and optical properties of electrochromic tungsten-containing nickel oxide films
    2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, p. 248-259Article in journal (Refereed) Published
    Abstract [en]

    Electrochromic NixW1-x oxide thin films with 0.5 < x < 1, were deposited by co-sputtering from one Ni and one W metal target. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in LiClO4 dissolved in propylene carbonate. It was found that the samples turned amorphous upon W addition and that the NixW1-x oxides probably consisted of hydrated Ni oxides and NiWO4. The charge insertion/extraction and optical modulation was unfortunately very modest. Moreover, an aging effect, resulting in a strong bleaching process of the samples was observed. Nevertheless, it was found that, for electrochromic applications, the advantage of W addition was that the transparency at the bleached state was enhanced for all compositions and for wavelengths of 400 nm up to NIR.

    National Category
    Materials Engineering
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-179763 (URN)10.1016/j.solmat.2013.04.001 (DOI)000338395100036 ()
    Conference
    10th International Meeting on Electrochromism (IME), Holland, MI, August 12-16, 2012
    Available from: 2012-08-22 Created: 2012-08-22 Last updated: 2017-12-07Bibliographically approved
    6. Electrochromic properties of nickel oxide based thin films sputter deposited in the presence of water vapor
    Open this publication in new window or tab >>Electrochromic properties of nickel oxide based thin films sputter deposited in the presence of water vapor
    Show others...
    2012 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 10, p. 3839-3842Article in journal (Refereed) Published
    Abstract [en]

    Electrochromic nickel oxide based thin films were prepared by reactive RF magnetron sputtering from metallic nickel in the presence of Ar, O-2 and H2O. The water vapor led to enhanced optical modulation and charge capacity. At a wavelength of 550 nm the bleached state transmittance was 0.73 and the transmittance for the colored state was 0.28 and 0.15 for water partial pressures of p(H2O)<10(-3) Pa and p(H2O) similar to 7 x 10(-2) Pa, respectively. The charge densities were 14 and 25 mC/cm(2) for p(H2O)<10(-3) Pa and P-H2O similar to 7 x 10(-2) Pa, respectively. The coloration efficiency was decreased with increased water partial pressure, from about 0.07 to 0.06 cm(2)/mC. Preliminary results show that the H2O promotes an amorphous structure and makes the films increasingly hydrous. 

    Keywords
    Nickel oxide, Electrochromism, RF magnetron sputtering, Water vapor, Thin film, Optical properties, Charge capacity
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-174595 (URN)10.1016/j.tsf.2011.08.030 (DOI)000302973400027 ()
    Available from: 2012-05-24 Created: 2012-05-22 Last updated: 2017-12-07Bibliographically approved
  • 13.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Backholm, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Georen, P
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel Oxide and Tungsten Oxide Thin Films: Ion Intercalation from Different Electrolytes2009In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 93, no 12, p. 2050-2055Article in journal (Refereed)
    Abstract [en]

    Electrochromic (EC) NiOz and WOy thin films were prepared by sputtering   and were used in a feasibility study aimed at investigating mixtures of   these two oxides. The object was to identify a suitable electrolyte,   compatible with both NiOz and WOy. To that end we carried out cyclic   voltammetry (CV) in potassium hydroxide (KOH), propionic acid, and   lithium perchlorate in propylene carbonate (Li-PC). WOy could be   coloured in propionic acid and Li-PC, while NiOz could be coloured only   in KOH. Both films showed best stability in Li-PC, which hence is well   suited for further studies of mixed NiOz and WOy.

  • 14.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel Doped Tungsten Oxide2009In: Advances in Transparent Electronics: From Materials to Devices, 2009Conference paper (Refereed)
  • 15.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and optical properties of electrochromic tungsten-containing nickel oxide films2014In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, p. 248-259Article in journal (Refereed)
    Abstract [en]

    Electrochromic NixW1-x oxide thin films with 0.5 < x < 1, were deposited by co-sputtering from one Ni and one W metal target. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in LiClO4 dissolved in propylene carbonate. It was found that the samples turned amorphous upon W addition and that the NixW1-x oxides probably consisted of hydrated Ni oxides and NiWO4. The charge insertion/extraction and optical modulation was unfortunately very modest. Moreover, an aging effect, resulting in a strong bleaching process of the samples was observed. Nevertheless, it was found that, for electrochromic applications, the advantage of W addition was that the transparency at the bleached state was enhanced for all compositions and for wavelengths of 400 nm up to NIR.

  • 16.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel-Tungsten Oxides.2012In: IME-10. Tenth International meeting on Electrochromism, Holland, MI USA, August 12-16, 2012., 2012, p. 17-Conference paper (Refereed)
  • 17.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kuzmin, A
    Institute of Solid State Physics, University of Latvia, Riga, Latvia.
    Purans, J
    Institute of Solid State Physics, University of Latvia, Riga, Latvia.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and composition of sputter-deposited nickel-tungsten oxide films2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 7, p. 2062-2066Article in journal (Refereed)
    Abstract [en]

    Films of mixed nickel-tungsten oxide, denoted NixW1-x oxide, were prepared by reactive DC magnetron co-sputtering from metallic targets and were characterized by Rutherford backscattering spectrometry. X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x<0.50 the films comprised a mixture of amorphous WO3 and nanosized NiWO4, at x = 0.50 the nanosized NiWO4 phase was dominating, and at x>0.50 the films contained nanosized NiO and NiWO4.

  • 18.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kuzmin, Alexei
    Purans, Juris
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and composition of sputter-deposited nickel-tungsten oxide films2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 7, p. 2062-2066Article in journal (Refereed)
    Abstract [en]

    Films of mixed nickel-tungsten oxide, denoted NixW1−x oxide, were prepared by reactive DC magnetron cosputtering from metallic targets and were characterized by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x<0.50 the films comprised a mixture of amorphous WO3 and nanosized NiWO4, at x=0.50 the nanosized NiWO4 phase was dominating, and at x>0.50 the films contained nanosized NiO and NiWO4.

  • 19.
    Green, Sara V
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Pehlivan, Esat
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in sputter deposited nickel-containing tungsten oxide films2012In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 99, p. 339-344Article in journal (Refereed)
    Abstract [en]

    Thin films of NixW1-x oxide were prepared by reactive DC magnetron co-sputtering and were investigated by optical and electrochemical measurements. Electrochromism was found only for 0<x<0.3 but not for 0.3<x<0.6, though films with x~0.4 could still sustain reversible charge insertion. The coloration efficiency was largest for 0.10<x<0.15. The charge capacity of the NixW1-x oxide films decreased upon increasing the value of x as a consequence of a decreasing ion diffusion coefficient leading to slower kinetics.

  • 20.
    Green, Sara V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Watanabe, M.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Oka, N.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Shigesato, Y.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Electrochromic properties of nickel oxide based thin films sputter deposited in the presence of water vapor2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 10, p. 3839-3842Article in journal (Refereed)
    Abstract [en]

    Electrochromic nickel oxide based thin films were prepared by reactive RF magnetron sputtering from metallic nickel in the presence of Ar, O-2 and H2O. The water vapor led to enhanced optical modulation and charge capacity. At a wavelength of 550 nm the bleached state transmittance was 0.73 and the transmittance for the colored state was 0.28 and 0.15 for water partial pressures of p(H2O)<10(-3) Pa and p(H2O) similar to 7 x 10(-2) Pa, respectively. The charge densities were 14 and 25 mC/cm(2) for p(H2O)<10(-3) Pa and P-H2O similar to 7 x 10(-2) Pa, respectively. The coloration efficiency was decreased with increased water partial pressure, from about 0.07 to 0.06 cm(2)/mC. Preliminary results show that the H2O promotes an amorphous structure and makes the films increasingly hydrous. 

  • 21. Johansson, M.
    et al.
    Alves, P.
    Green, S.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Near-infrared electrochromism in crystalline tungsten oxide thin films2010Conference paper (Refereed)
  • 22.
    Malmgren, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Anomalous diffusion of ions in electrochromic tungsten oxide films2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 247, p. 252-257Article in journal (Refereed)
    Abstract [en]

    Amorphous tungsten oxide thinfilms were deposited by sputtering at different O2/Ar ratios onto conducting substrates. Ion intercalation and diffusion in thefilms was studied by electrochemical impedance spectroscopy measurements in the frequency range 10 mHz–100 kHz and for potentials between 1.0 and 3.2 V vs. Li/Li+, using the film as working electrode in a Li+ containing electrolyte. The impedance data were in very good agreement with anomalous diffusion models. Different models were found to be applicable at potentials >1.8 V and <1.8 V. At high potentials ion intercalation was found to be reversible and an anomalous diffusion model describing ion hopping was favored. At low potentials ion intercalation was found to be irreversible and ion trapping takes place. In this latter range an anomalous diffusion model for the case of non-conserved number of charge carriers gave the best fit to experimentaldata. We obtained potential dependent diffusion coefficients in the range from 109 to 1011cm2/s, and anomalous diffusion exponents in the range 0.1 to 0.4, with the films deposited at lower O2/Ar ratios exhibiting the higher values.

  • 23.
    Niklasson, Gunnar A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Delsol, B.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lansåker, Pia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Chronopotentiometry on indium-tin oxide films: Evidence for lithium intercalation2010Conference paper (Refereed)
  • 24.
    Niklasson, Gunnar A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Backholm, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Determination of electronic structure by impedance spectroscopy2010In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 356, no 11-17, p. 705-709Article in journal (Refereed)
    Abstract [en]

    We present a novel method, based on electrochemical intercalation and impedance spectroscopy, to determine the electronic density of states of disordered transition metal oxides. Specifically, we have determined the "electrochemical density of states" of tungsten and iridium oxide thin films over energy ranges as wide as 1-2 eV. Our experimental results show a number of qualitative features exhibited by state-of-the-art band structure computations. Differences in details are probably due to the disordered, porous and sometimes amorphous nature of our films. The results suggest that the impedance spectroscopy method can be used to obtain the density of states only if the conduction band states are localized. The electrochemical density of states is often smaller than the computed one due to kinetic effects, i.e. very slow relaxations of the charge carriers. Nevertheless, our sensitive method opens new vistas for studying the electronic structure of disordered materials.

  • 25. Smulko, J.
    et al.
    Azens, A.
    Marsal, R.
    Kish, L. B.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Application of 1/f current noise for quality and age monitoring of electrochromic devices2008In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 92, no 8, p. 914-918Article in journal (Refereed)
    Abstract [en]

    This is a continuation of an earlier study on 1/f noise in electrochromic (EC) devices undergoing discharge via a resistor. The EC devices comprised films of W oxide and Ni-V oxide joined by a polymer electrolyte, and with this three-layer stack positioned between transparent conducting In2O3:Sn films backed by polyester foils. We also investigated "symmetrical" devices with two identical films of W oxide or Ni-V oxide. The power spectral density S-i at fixed frequency scaled with current (1) as S-i similar to I-2. Color/bleach cycling for about 2500 times degraded the optical properties and homogeneity of the EC devices and increased the 1/f noise intensity by a factor of four, which confirms the earlier assumption that 1/f noise has a good potential to serve as quality and aging assessment for EC devices. Studies of "symmetrical" devices proved that the noise was mainly associated with the Ni oxide, and measurements on individual parts of an EC device indicated that the 1/f noise originated from localized areas.

  • 26.
    Valyukh, I
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Arwin, H
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wäckelgård, Ewa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Optical Properties of Amorphous Tungsten Oxide Films Deposited by Reactive DC Magnetron Sputtering2009Conference paper (Refereed)
  • 27.
    Valyukh, I
    et al.
    Laboratory of Applied Optics, Dept of Physics, Chemistry and Biology, Linköping University, Linköping.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Valyukh, S
    Laboratory of Applied Optics, Dept of Physics, Chemistry and Biology, Linköping University, Linköping.
    Arwin, H
    Laboratory of Applied Optics, Dept of Physics, Chemistry and Biology, Linköping University, Linköping.
    Optical properties of thin films of mixed Ni-W oxide made by reactive DC magnetron sputtering2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 9, p. 2914-2918Article in journal (Refereed)
    Abstract [en]

    Thin films of NixW1-x oxides with x = 0.05, 0.19, 0.43 and 0.90 were studied. Films with thicknesses in the range 125-250 nm were deposited on silicon wafers at room temperature by reactive DC magnetron co-sputtering from targets of Ni and W. The films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). XRD spectra and SEM micrographs showed that all films were amorphous and possessed a columnar structure. The ellipsometric angles psi and Delta of as-deposited films were measured by a rotating analyzer ellipsometer in the UV-visible-near infrared range (0.63-6.18 eV) and by an infrared Fourier transform rotating compensator ellipsometer in the 500-5200 cm(-1) wavenumber range. SE measurements were performed at angles of incidence of from 50 degrees to 70 degrees. Parametric models were used to extract thicknesses of the thin films and overlayers of NixW1-x oxide at different compositions, band gaps and optical constants. Features in the optical spectra of the NixW1-x oxides were compared with previous data on tungsten oxide, nickel oxide and nickel tungstate.

  • 28.
    Valyukh, Iryna
    et al.
    Department of Material Science, Dalarna University.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Arwin, Hans
    Laboratory of Applied Optics, Department of Physics, Chemistry and Biology, Linköping University.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wäckelgård, Ewa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Spectroscopic ellipsometry characterization of electrochromic tungsten oxide and nickel oxide thin films made by sputter deposition2010In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 94, no 5, p. 724-732Article in journal (Refereed)
    Abstract [en]

    Electrochromic films of tungsten oxide and nickel oxide were made by reactive dc magnetron sputtering and were characterized by X-ray diffraction, Rutherford backscattering spectrometry, scanning electron microscopy, and atomic force microscopy. The optical properties were investigated in detail by spectroscopic ellipsometry and spectrophotometry, using a multiple-sample approach. The W oxide film was modeled as a homogeneous isotropic layer, whereas the Ni oxide film was modeled as an anisotropic layer with the optical axis perpendicular to the surface. Parametric models of the two layers were then used to derive complex refractive index in the 300-1700-nm-range, film thickness, and surface roughness. A band gap of 3.15 eV was found for the W oxide film, using a Tauc-Lorentz parameterization. For the Ni oxide film, taken to have direct optical transitions, band gaps along the optical axis, perpendicular to it, and in an isotropic intermediate layer at the bottom of the film were found to be 3.95, 3.97, and 3.63 eV, respectively. Parameterization for the Ni oxide was made by use of the Lorentz model.

  • 29.
    Valyukh, Iryna
    et al.
    Laboratory of Applied Optics, Dept of Physics, Chemistry and Biology, Linköping University.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Arwin, Hans
    Laboratory of Applied Optics, Dept of Physics, Chemistry and Biology, Linköping University.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 4, p. 044308-Article in journal (Refereed)
    Abstract [en]

    Films of NixW1−x oxide with 0.05 ≤ x ≤ 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract accurate data on the dielectric function in the photon range 0.062 to 5.62 eV. The results for 0.62 to 5.62 eV were compared with computations from the Bruggeman effective medium theory applied to two nanostructural models: one representing a random mixture of structural entities characterized by the dielectric functions of WO3 and NiWO4 and the other describing a random mixture of WO3 and NiO. Unambiguous evidence was found in favor of the former model, and hence the films are composed of nanosized tungsten oxide and nickel tungstate. This agrees excellently with an earlier investigation of ours on NixW1−x oxide films, where nanostructure was inferred from Raman spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction.

  • 30.
    Valyukh, Iryna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Valyukh, Sergiy
    Arwin, Hans
    Optical properties of thin films of mixed Ni–W oxide made by reactive DCmagnetron sputtering2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 9, p. 2914-2918Article in journal (Refereed)
    Abstract [en]

    Thin films of NixW1−x oxides with x=0.05, 0.19, 0.43 and 0.90 were studied. Films with thicknesses in the range 125–250 nm were deposited on silicon wafers at room temperature by reactive DC magnetron co-sputtering from targets of Ni and W. The films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). XRD spectra and SEMmicrographs showed that all films were amorphous and possessed a columnar structure. The ellipsometric angles Ψ and Δ of as-deposited films were measured by a rotating analyzer ellipsometer in the UV–visible-near infrared range (0.63–6.18 eV) and by an infrared Fourier transform rotating compensator ellipsometer in the 500–5200 cm−1 wavenumber range. SE measurementswere performed at angles of incidence of from50 ° to 70 °. Parametricmodelswere used to extract thicknesses of the thin films and overlayers of NixW1−x oxide at different compositions, band gaps and optical constants. Features in the optical spectra of the NixW1−x oxideswere compared with previous data on tungsten oxide, nickel oxide and nickel tungstate.

  • 31.
    Århammar, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pietzsch, Annette
    MAX-lab, Lunds universitet, Lund.
    Bock, Nicolas
    Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
    Holmström, Erik
    Instituto di Fisica, Universidad Austral de Chile, Valdivia, Chile.
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Gråsjö, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Zhao, Shuxi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Peery, T
    Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
    Hennies, Franz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Amerioun, Shahrad
    Sandvik Tooling, R and D, Stockholm.
    Foehlisch, Alexander
    Insitute for Methods and Instrumentation in Synchrotron Radiation Research G-12, Helmhotz-Zentrum Berlin für Materialien und Energie, Berlin, Tyskland.
    Schlappa, Justine
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Schmitt, Thorsten
    Swiss Light Source, Paul Scherrer Institut, Villigen, Schweiz.
    Strocov, Vladimir N
    Swiss Light Source, Paul Scherrer Institut, Villigen, Schweiz.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wallace, Duane C
    Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Unveiling the complex electronic structure of amorphous metal oxides2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 16, p. 6355-6360Article in journal (Refereed)
    Abstract [en]

    Amorphous materials represent a large and important emerging area of material's science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today's integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5-10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.

1 - 31 of 31
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