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  • 1.
    Aboulfadl, Hisham
    et al.
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsen, Jes K
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Platzer Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Microstructural Characterization of Sulfurization Effects in Cu(In,Ga)Se-2 Thin Film Solar Cells2019Inngår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, nr 2, s. 532-538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface sulfurization of Cu(In,Ga)Se-2 (CIGSe) absorbers is a commonly applied technique to improve the conversion efficiency of the corresponding solar cells, via increasing the bandgap towards the heterojunction. However, the resulting device performance is understood to be highly dependent on the thermodynamic stability of the chalcogenide structure at the upper region of the absorber. The present investigation provides a high-resolution chemical analysis, using energy dispersive X-ray spectrometry and laser-pulsed atom probe tomography, to determine the sulfur incorporation and chemical re-distribution in the absorber material. The post-sulfurization treatment was performed by exposing the CIGSe surface to elemental sulfur vapor for 20 min at 500 degrees C. Two distinct sulfur-rich phases were found at the surface of the absorber exhibiting a layered structure showing In-rich and Ga-rich zones, respectively. Furthermore, sulfur atoms were found to segregate at the absorber grain boundaries showing concentrations up to similar to 7 at% with traces of diffusion outwards into the grain interior.

  • 2.
    Fritze, Stefan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Malinovskis, Paulius
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    von Fieandt, Linus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Hard and crack resistant carbon supersaturated refractory nanostructured multicomponent coatings2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikkel-id 14508Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The combination of ceramic hardness with high crack resistance is a major challenge in the design of protective thin films. High entropy alloys have shown in earlier studies promising mechanical properties with a potential use as thin film materials. In this study, we show that small amounts of carbon in magnetron-sputtered multicomponent CrNbTaTiW films can lead to a significant increase in hardness. The film properties were strongly dependent on the metal composition and the most promising results were observed for TaW-rich films. They crystallised in a bcc structure with a strong (110) texture and coherent grain boundaries. It was possible to deposit films with 8 at.% C in a supersaturated solid-solution into the bcc structure without carbide formation. A major effect of carbon was a significant grain refinement, reducing the column diameter from approximately 35 to 10 nm. This resulted in an increase in hardness from 14.7 to 19.1 GPa while the reduced E-modulus stayed constant at 322 GPa. The carbon-containing films exhibited extremely little plastic deformation around the indent and no cracks were observed. These results show that supersaturation of carbon into high entropy films can be a promising concept to combine superior hardness with high crack resistance.

    Fulltekst (pdf)
    FULLTEXT01
  • 3.
    Jablonka, Lukas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Highly conductive ultrathin Co films by high-power impulse magnetron sputtering2018Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, nr 4, artikkel-id 043103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ultrathin Co films deposited on SiO2 with conductivities exceeding that of Cu are demonstrated. Ionized deposition implemented by high-power impulse magnetron sputtering (HiPIMS) is shown to result in smooth films with large grains and low resistivities, namely, 14 mu Omega cm at a thickness of 40 nm, which is close to the bulk value of Co. Even at a thickness of only 6 nm, a resistivity of 35 mu Omega cm is obtained. The improved film quality is attributed to a higher nucleation density in the Co-ion dominated plasma in HiPIMS. In particular, the pulsed nature of the Co flux as well as shallow ion implantation of Co into SiO2 can increase the nucleation density. Adatom diffusion is further enhanced in the ionized process, resulting in a dense microstructure. These results are in contrast to Co deposited by conventional direct current magnetron sputtering where the conductivity is reduced due to smaller grains, voids, rougher interfaces, and Ar incorporation. The resistivity of the HiPIMS films is shown to be in accordance with models by Mayadas-Shatzkes and Sondheimer which consider grain-boundary and surface-scattering.

    Fulltekst (pdf)
    fulltext
  • 4.
    Johansson, Kristina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. Uppsala Univ, Angstrom Lab, Dept Chem, Inorgan Res Programme, Box 538, SE-75121 Uppsala, Sweden.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Fritze, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition2018Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 349, s. 529-539Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicomponent nitride coatings of the Hf-Nb-Ti-V-Zr system with different Hf content (0-18 at.%) were deposited using reactive dc magnetron sputtering. Coatings with lower Hf content (0-7 at.%) were found to consist of a single solid solution phase with NaCl-type structure (space group Fm-3m). Coatings with higher Hf content (10-18 at.%) showed a two-phase material consisting of cubic Fm-3m and tetragonal I4/m:run solid solution phase. The lattice distortion, estimated by calculating the delta-parameter under the assumption of a single solid solution phase, varied between 3.8 and 4.0% and slightly decreased with increasing Hf content. SEM and TEM cross section images showed a columnar microstructure with columns that were frayed on the surface or throughout the whole column. The column size decreased as Hf content increased. The hardness increased from 8 to 19 GPa with increased Hf content, which most probably is related to the change in microstructure rather than change in lattice distortion. The electrical resistivity for all samples ranged between 231 and 286 mu Omega cm.

  • 5.
    Karlsson, Dennis
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lindwall, Greta
    Royal Inst Technol KTH, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Lundback, Andreas
    Lulea Univ Technol, SE-97187 Lulea, Sweden.
    Amnebrink, Mikael
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Bostrom, Magnus
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Schuisky, Mikael
    Sandvik AB, Sandvik Addit Mfg, Box 510, SE-10130 Stockholm, Sweden.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Binder jetting of the AlCoCrFeNi alloy2019Inngår i: ADDITIVE MANUFACTURING, ISSN 2214-8604, Vol. 27, s. 72-79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High density components of an AlCoCrFeNi alloy, often described as a high-entropy alloy, were manufactured by binder jetting followed by sintering. Thermodynamic calculations using the CALPHAD approach show that the high-entropy alloy is only stable as a single phase in a narrow temperature range below the melting point. At all other temperatures, the alloy will form a mixture of phases, including a sigma phase, which can strongly influence the mechanical properties. The phase stabilities in built AlCoCrFeNi components were investigated by comparing the as-sintered samples with the post-sintering annealed samples at temperatures between 900 degrees C and 1300 degrees C. The as-sintered material shows a dominant B2/bcc structure with additional fcc phase in the grain boundaries and sigma phase precipitating in the grain interior. Annealing experiments between 1000 degrees C and 1100 degrees C inhibit the sigma phase and only a B2/bcc phase with a fcc phase is observed. Increasing the temperature further suppresses the fcc phase in favor for the B2/bcc phases. The mechanical properties are, as expected, dependent on the annealing temperature, with the higher annealing temperature giving an increase in yield strength from 1203 MPa to 1461 MPa and fracture strength from 1996 MPa to 2272 MPa. This can be explained by a hierarchical microstructure with nano-sized precipitates at higher annealing temperatures. The results enlighten the importance of microstructure control, which can be utilized in order to tune the mechanical properties of these alloys. Furthermore, an excellent oxidation resistance was observed with oxide layers with a thickness of less than 5 mu m after 20 h annealing at 1200 degrees C, which would be of great importance for industrial applications.

    Fulltekst (pdf)
    fulltext
  • 6.
    Keller, Jan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Bilousov, Oleksandr V.
    Solibro Research.
    Wallin, Erik
    Solibro Research.
    Lundberg, Olle
    Solibro Research.
    Neerken, Janet
    Carl von Ossietzky University Oldenburg.
    Heise, Stephan
    Carl von Ossietzky University Oldenburg.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Platzer-Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Effect of Cu content on post‐sulfurization of Cu(In,Ga)Se2 films and corresponding solar cell performance2019Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 216, nr 20, artikkel-id 1900472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, the effect of the initial copper content of co‐evaporated Cu(In1−x,Gax)Se2 (CIGS) absorber films on the impact of a post‐annealing step in elemental sulfur atmosphere is studied. The Cu concentration is varied over a wide range ([Cu]/[III] = CGI = 0.57–1.23), allowing to identify composition‐dependent trends in phase formation, chemical rearrangements, and solar cell performance after sulfurization. For all samples, a ternary CuInS2 layer forms at the surface. In addition, sulfur 1) is incorporated in randomly distributed CuIn(S,Se)2 mixed crystals underneath CuInS2; 2) diffuses into multidimensional defects (e.g., dislocations and grain boundaries); and 3) is bound in Na–In–S surface plates. It is found that Cu‐poor absorber composition (CGI ≤ 0.82) favors CuInS2 growth as compared with close‐stoichiometric CIGS films, driven by a faster diffusion of Cu toward the surface. For Cu‐rich absorbers (CGI > 1), Se—S exchange is significantly accelerated, presumably by the presence of Cu2−xSe phases reacting to Cu2−xS and eventually catalyzing CuInS2 formation. Finally, open‐circuit voltage (VOC), fill factor (FF), and efficiency (η) of corresponding solar cells increase after sulfurization with increasing CGI until stoichiometry is reached. The result is explained by a mitigated Cu depletion of the absorber bulk after sulfurization for close‐stoichiometric CIGS.

  • 7.
    Keller, Jan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chalvet, Francis
    Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Joel, Jonathan
    Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Aijaz, Asim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Stolt, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Solibro Res AB, Vallvagen 5, S-75151 Uppsala, Sweden.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Effect of KF absorber treatment on the functionality of different transparent conductive oxide layers in CIGSe solar cells2018Inngår i: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, nr 1, s. 13-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This contribution studies the impact of the KF-induced Cu(In,Ga)Se2 (CIGSe) absorber modification on the suitability of different transparent conductive oxide (TCO) layers in solar cells. The TCO material was varied between ZnO:Al (AZO), ZnO:B (BZO), and In2O3:H (IOH). It is shown that the thermal stress needed for optimized TCO properties can establish a transport barrier for charge carriers, which results in severe losses in fill factor (FF) for temperatures >150°C. The FF losses are accompanied by a reduction in open circuit voltage (Voc) that might originate from a decreased apparent doping density (Nd,app) after annealing. Thermally activated redistributions of K and Na in the vicinity of the CdS/(Cu,K)-In-Se interface are suggested to be the reason for the observed degradation in solar cell performance. The highest efficiency was measured for a solar cell where the absorber surface modification was removed and a BZO TCO layer was deposited at a temperature of 165°C. The presented results highlight the importance of well-designed TCO and buffer layer processes for CIGSe solar cells when a KF post deposition treatment (KF-PDT) was applied.

  • 8.
    Keller, Jan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Chen, Wei-Chao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Bifacial Cu(In,Ga)Se2 solar cells using hydrogen‐doped In2O3 films as a transparent back contact2018Inngår i: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, nr 10, s. 846-858Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrogen‐doped In2O3 (IOH) films are used as a transparent back contact in bifacial Cu(In,Ga)Se2 (CIGS) solar cells. The effect of the IOH thickness and the impact of the sodium incorporation technique on the photovoltaic parameters are studied, and clear correlations are observed. It is shown that a loss in short circuit current density (JSC) is the major limitation at back side illumination. The introduction of a thin Al2O3 layer on top of the IOH significantly increases the collection efficiency (ϕ(x)) for electrons generated close to the back contact. In this way, the JSC loss can be mitigated to only ~ 25% as compared with front side illumination. The Al2O3 film potentially reduces the interface defect density or, alternatively, creates a field effect passivation. In addition, it prevents the excessive formation of Ga2O3 at the CIGS/IOH interface, which is found otherwise when a NaF layer is added before absorber deposition. Consequently, detrimental redistributions in Ga and In close to the back contact can be avoided. Finally, a bifacial CIGS solar cell with an efficiency (η) of η = 11.0% at front and η = 6.0% at back side illumination could be processed. The large potential for further improvements is discussed.

  • 9.
    Keller, Jan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Shariati, Masumeh-Nina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Aijaz, Asim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Using hydrogen‐doped In2O3 films as a transparent back contact in (Ag,Cu)(In,Ga)Se2 solar cells2018Inngår i: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, nr 3, s. 159-170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study evaluates the potential of hydrogen‐doped In2O3 (IOH) as a transparent back contact material in (Agy,Cu1‐y)(In1‐x,Gax)Se2 solar cells. It is found that the presence of Na promotes the creation of Ga2O3 at the back contact during (Agy,Cu1‐y)(In1‐x,Gax)Se2 growth. An excessive Ga2O3 formation results in a Ga depletion, which extends deep into the absorber layer. Consequently, the beneficial back surface field is removed and a detrimental reversed electrical field establishes. However, for more moderate Ga2O3 amounts (obtained with reduced Na supply), the back surface field can be preserved. Characterization of corresponding solar cells suggests the presence of an ohmic back contact, even at absorber deposition temperatures of 550°C. The best solar cell with an IOH back contact shows a fill factor of 74% and an efficiency (η) of 16.1% (without antireflection coating). The results indicate that Ga2O3 does not necessarily act as a transport barrier in the investigated system. Observed losses in open circuit voltage (VOC) as compared to reference samples with a Mo back contact are ascribed to a lower Na concentration in the absorber layer.

    Fulltekst (pdf)
    fulltext
  • 10.
    Larsen, Jes K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lundberg, Olle
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Jarmar, Tobias
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Scragg, Jonathan J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Platzer Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Sulfurization of Co-Evaporated Cu(In,Ga)Se-2 as a Postdeposition Treatment2018Inngår i: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, nr 2, s. 604-610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is investigated if the performance of Cu(In,Ga)Se-2 (CIGSe) solar cells produced by co-evaporation can be improved by surface sulfurization in a postdeposition treatment. The expected benefit would be the formation of a sulfur/selenium gradient resulting in reduced interface recombination and increased open-circuit voltage. In the conditions used here it was, however, found that the reaction of the CIGSe layer in a sulfur environment results in the formation of a CuInS2 (CIS) surface phase containing no or very little selenium and gallium. At the same time, a significant pile up of gallium was observed at the CIGSe/CIS boundary. This surface structure was formed for a wide range of annealing conditions investigated in this paper. Increasing the temperature or extending the time of the dwell stage had a similar effect on the material. The gallium enrichment and CIS surface layer widens the surface bandgap and therefore increases the open-circuit voltage. At the same time, the fill factor is reduced, since the interface layer acts as an electron barrier. Due to the balance of these effects, the conversion efficiency could not be improved.

    Fulltekst (pdf)
    fulltext
  • 11.
    Larsen, Jes K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Larsson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Saini, Nishant
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Ren, Yi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Midsummer AB, Elect Hojden 6, S-17543 Jarfalla, Sweden.
    Biswal, Adyasha
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany.
    Hauschild, Dirk
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany.
    Weinhardt, Lothar
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany;Univ Nevada, Dept Chem & Biochem, Las Vegas UNLV, 4505 Maryland Pkwy, Las Vegas, NV 89154 USA.
    Heske, Clemens
    KIT, Inst Photon Sci & Synchrotron Radiat IPS, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany;KIT, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 18-20, D-76128 Karlsruhe, Germany;Univ Nevada, Dept Chem & Biochem, Las Vegas UNLV, 4505 Maryland Pkwy, Las Vegas, NV 89154 USA.
    Platzer Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Cadmium Free Cu2ZnSnS4 Solar Cells with 9.7% Efficiency2019Inngår i: Advanced Energy Material, ISSN 1614-6832, Vol. 9, nr 21, artikkel-id 1900439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cu2ZnSnS4(CZTS) thin-film solar cell absorbers with different bandgaps can be produced by parameter variation during thermal treatments. Here, the effects of varied annealing time in a sulfur atmosphere and an ordering treatment of the absorber are compared. Chemical changes in the surface due to ordering are examined, and a downshift of the valence band edge is observed. With the goal to obtain different band alignments, these CZTS absorbers are combined with Zn1−xSnxOy (ZTO) or CdS buffer layers to produce complete devices. A high open circuit voltage of 809 mV is obtained for an ordered CZTS absorber with CdS buffer layer, while a 9.7% device is obtained utilizing a Cd free ZTO buffer layer. The best performing devices are produced with a very rapid 1 min sulfurization, resulting in very small grains.

    Fulltekst (pdf)
    fulltext
  • 12.
    Larsson, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Atomic layer deposition of amorphous tin-gallium oxide films2019Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikkel-id 030906Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A wide range of applications benefit from transparent semiconducting oxides with tunable electronic properties, for example, electron transport layers in solar cell devices, where the electron affinity is a key parameter. Presently, a few different ternary oxides are used for this purpose, but the attainable electron affinity range is typically limited. In this study, the authors develop a low-temperature atomic layer deposition (ALD) process to grow amorphous Sn1-xGaxOy thin films from dimethylamino-metal complexes and water. This oxide is predicted to provide a wide selection of possible electron affinity values, from around 3 eV for pure Ga2O3 to 4.5 eV for pure SnO2. The ALD process is evaluated for deposition temperatures in the range of 105-195 degrees C by in situ quartz crystal microbalance and with ex situ film characterization. The growth exhibits an ideal-like behavior at 175 degrees C, where the film composition can be predicted by a simple rule of mixture. Depending on film composition, the growth per cycle varies in the range of 0.6-0.8 angstrom at this temperature. Furthermore, the film composition for a given process appears insensitive to the deposition temperature. From material characterization, it is shown that the deposited films are highly resistive, fully amorphous, and homogeneous, with moderate levels of impurities (carbon, nitrogen, and hydrogen). By tailoring the metal cation ratio in films grown at 175 degrees C, the optical bandgap can be varied in the range from 2.7 eV for SnO2 to above 4.2 eV for Ga2O3. The bandgap also varies significantly as a function of deposition temperature. This control of properties indicates that Sn1-xGaxOy is a promising candidate for an electron transport layer material in a wide electron affinity range. Published by the AVS.

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    fulltext
  • 13.
    Malinovskis, Paulius
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Fritze, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    von Fieandt, Linus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Cedervall, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Rehnlund, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Synthesis and characterization of multicomponent (CrNbTaTiW)C films for increased hardness and corrosion resistance2018Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 149, s. 51-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicomponent carbide thin films of (CrNbTaTiW)C (30–40 at.% C) with different metal contents were depos-ited at different temperatures using non-reactive DC magnetron sputtering. The lattice distortion for the metallattice was estimated to vary from about 3 to 5%. Most films crystallized in the cubic B1 structure but Ta/W-rich films deposited at 600 °C exhibited a tetra gonal distortion. X-ray diffraction results sh ow that near-equimolar films exhibited a strong (111) texture. In contrast, Ta/W-rich films exhibited a shift from (111) to(100) texture at 450 °C. The in-plane relationship was determined to MC(111)[-12-1]//Al2O3(001)[110] with alattice mismatch of about 11% along the Al2O3[110] direction. A segregation of Cr to the grain boundaries was ob-served in all films. The microstructure was found to be the most important factor for high hardness. Less denseNb-rich and near-equimolar films deposited at low tem peratures exhib ited the low est hardnes s (12 GPa),while very dense Ta/W-rich high temperature films were found to be the hardest (36 GPa). No correlation wasfound between the lattice distortion and the hardness. Corrosion studies revealed that the multicomponentfilms exhibited excellent corrosion resistance, superior to that of a reference hyper-duplex stainless steel, in1.0 M HCl.

    Fulltekst (pdf)
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  • 14.
    Marattukalam, Jithin J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Pacheco, Victor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Karlsson, Dennis
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lindwall, Johan
    Forsberg, Fredrik
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Development of process parameters for selective laser melting of a Zr-based bulk metallic glass2020Inngår i: Additive Manufacturing, ISSN 2214-8604, Vol. 33, artikkel-id 101124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Parameters for selective laser melting of Zr59.3Cu28.8Al10.4Nb1.5 (trade name AMZ4), allowing crack-free bulk metallic glass with low porosity, have been developed. The phase formation was found to be strongly influenced by the heating power of the laser. X-ray amorphous samples were obtained with laser power at and below 75 W. The as-processed bulk metallic glass was found to devitrify by a two-stage crystallization process within which the presence of oxygen was concluded to play an essential role. At laser powers above 75 W, the observed crystallites were found to be a cubic phase (Cu2Zr4O). The hardness and Young’s modulus in the as-processed samples was found to increase marginally with increased fraction of the crystalline phase.

    Fulltekst (pdf)
    fulltext
  • 15.
    Shinde, Deodatta
    et al.
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Fritze, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Malinovskis, Paulius
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Stiller, Krystyna
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Elemental Distribution in CrNbTaTiW-C High Entropy Alloy Thin Films2019Inngår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, nr 2, s. 489-500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The microstructure and distribution of the elements have been studied in thin films of a near-equimolar CrNbTaTiW high entropy alloy (HEA) and films with 8 at.% carbon added to the alloy. The films were deposited by magnetron sputtering at 300 degrees C. X-ray diffraction shows that the near-equimolar metallic film crystallizes in a single-phase body centered cubic (bcc) structure with a strong (110) texture. However, more detailed analyses with transmission electron microscopy (TEM) and atom probe tomography (APT) show a strong segregation of Ti to the grain boundaries forming a very thin Ti-Cr rich interfacial layer. The effect can be explained by the large negative formation enthalpy of Ti-Cr compounds and shows that CrNbTaTiW is not a true HEA at lower temperatures. The addition of 8 at.% carbon leads to the formation of an amorphous structure, which can be explained by the limited solubility of carbon in bcc alloys. TEM energy-dispersive X-ray spectroscopy indicated that all metallic elements are randomly distributed in the film. The APT investigation, however, revealed that carbide-like clusters are present in the amorphous film.

  • 16.
    Song, Man
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhao, Jie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Meng, Yu
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Hou, Peng-Xiang
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process2019Inngår i: CHEMNANOMAT, ISSN 2199-692X, Vol. 5, nr 9, s. 1144-1151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report an efficient one-step method to achieve highly reduced graphene oxide (rGO) hydrogel doped with nitrogen where the rGO sheets are interconnected forming a porous structure by means of hydrothermal process. During the synthesis, ammonium formate is used as reducing reagent and simultaneously as nitrogen supplier, which delivers nitrogen-doped rGO (NRGO) hydrogel that exhibits C/O atomic ratio as high as at ~11.1 and contains decent ~5.4 at.% nitrogen. As comparison, the reduction efficiency is only half of the value and no nitrogen doping can be obtained when L-ascorbic acid is used as reducing reagent. The resultant NRGO shows enhanced electrocatalytic ability for oxygen reduced reaction indicating its great potential of the one-step method for the catalyst and energy applications. 

  • 17.
    von Fieant, Kristina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Johansson, Fredrik O. L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Balmes, Olivier
    MAX IV Laboratory, Lund University, PO Box 118, SE-22100 Lund, Sweden.
    Lindblad, Rebecka
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lindblad, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    In Situ Formation of Ge Nanoparticles by Annealing of Al-Ge‑N ThinFilms Followed by HAXPES and XRD2019Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, nr 16, s. 11100-11109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ge nanoparticles embedded in thin films have attracted a lot of attention due to their promising optical and electronic properties that can be tuned by varying the particle size and choice of matrix material. In this study, Ge nanoparticle formation was investigated for Al-Ge-N based thin films by simultaneous measurements of HAXPES and grazing incidence XRD during in situ annealing in vacuum conditions. As-deposited Al-Ge-N thin films, synthesized by reactive dc magnetron sputtering, consisted of a nanocrystalline (Al1–xGex)Ny solid solution and an amorphous tissue phase of Ge3Ny. Upon annealing to 750 °C, elemental Ge was formed shown by both HAXPES and XRD measurements, and N2 gas was released as measured by a mass spectrometer. Postannealed ex situ analysis by SEM and TEM showed that the elemental Ge phase formed spherical nanoparticles on the surface of the film, with an average size of 210 nm. As the annealing temperature increased further to 850 °C, the Ge particles on the film surface evaporated, while the phase segregation of Ge still could be observed within the film. Thus, these results show the possibility for a controlled synthesis of Ge nanoparticles through annealing of Al-Ge-N thin films to produce materials suitable for use in electronic or optoelectronic devices.

  • 18.
    von Fieant, Kristina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Paschalidou, Eirini-Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Srinath, Aishwarya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Soucek, Pavel
    Masaryk Univ, Dept Phys Elect, Brno, Czech Republic.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Multi-component (Al,Cr,Nb,Y,Zr)N thin films by reactive magnetron sputter deposition for increased hardness and corrosion resistance2020Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 693, artikkel-id 137685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-component nitride thin films in the Al-Cr-Nb-Y-Zr system with non-equimolar composition have been deposited by reactive dc magnetron sputtering. The substrate temperature and substrate bias have been varied, from room temperature to 700 degrees C and from 0 to -200 V respectively. The relationship between these varied growth conditions on the structure, morphology, mechanical and corrosion properties of the films have been probed. All films consisted of a single solid solution with a NaCl-type structure, as shown by X-ray diffraction. However, elemental energy dispersive spectroscopy maps, obtained in the scanning transmission electron microscope, indicated that there could be partial segregation of Al, Cr and Y atoms within the grains. The microstructure of the films became denser, more fine-grained and smoother as the bias and temperature were increased. Nanoindentation showed that the hardness of the films increased with both bias and temperature, reaching a maximum of 27 +/- 2 GPa. The corrosion resistance of the films, studied by performing potentiodynamic polarisation curves in 1 M HCl, was also found to be improved when compared to a commercially available hyper-duplex stainless steel and a ternary reference (Nb,Zr)N thin film as well.

  • 19.
    Wu, Jiyue
    et al.
    Queen Mary Univ London, Sch Engn & Mat Sci, Mile End Rd, London E1 4NS, England.
    Mahajan, Amit
    Queen Mary Univ London, Sch Engn & Mat Sci, Mile End Rd, London E1 4NS, England.
    Riekehr, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Hangfeng
    Queen Mary Univ London, Sch Biol & Chem Sci, Mile End Rd, London E1 4NS, England.
    Yang, Bin
    Univ Chester, Fac Sci & Engn, Dept Elect & Elect Engn, Thornton Sci Pk, Chester CH2 4NU, Cheshire, England.
    Meng, Nan
    Queen Mary Univ London, Sch Engn & Mat Sci, Mile End Rd, London E1 4NS, England.
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Yan, Haixue
    Queen Mary Univ London, Sch Engn & Mat Sci, Mile End Rd, London E1 4NS, England.
    Perovskite Sr-x(Bi1-xNa0.97-xLi0.03)(0.5)TiO3 ceramics with polar nano regions for high power energy storage2018Inngår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 50, s. 723-732Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dielectric capacitors are very attractive for high power energy storage. However, the low energy density of these capacitors, which is mainly limited by the dielectric materials, is still the bottleneck for their applications. In this work, lead-free single-phase perovskite Srx(Bi1-xNa0.97-xLi0.03)(0.5)TiO3 (x = 0.30 and 0.38) bulk ceramics, prepared using solid-state reaction method, were carefully studied for the dielectric capacitor application. Polar nano regions (PNRs) were created in this material using co-substitution at A-site to enable relaxor behaviour with low remnant polarization (P-r) and high maximum polarization (P-max). Moreover, P-max was further increased due to the electric field induced reversible phase transitions in nano regions. Comprehensive structural and electrical studies were performed to confirm the PNRs and reversible phase transitions. And finally a high energy density (1.70 J/cm(3)) with an excellent efficiency (87.2%) was achieved using the contribution of field-induced rotations of PNRs and PNR-related reversible transitions in this material, making it among the best performing lead-free dielectric ceramic bulk material for high energy storage.

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