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Elofsson, V., Almyras, G., Lü, B., Garbrecht, M., Boyd, R. & Sarakinos, K. (2018). Structure formation in Ag-X (X = Au, Cu) alloys synthesized far-from-equilibrium. Journal of Applied Physics, 123(16)
Open this publication in new window or tab >>Structure formation in Ag-X (X = Au, Cu) alloys synthesized far-from-equilibrium
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2018 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 16Article in journal (Refereed) Published
Abstract [en]

We employ sub-monolayer, pulsed Ag and Au vapor fluxes, along with deterministic growth simulations, and nanoscale probes to study structure formation in miscible Ag-Au films synthesized under far-from-equilibrium conditions. Our results show that nanoscale atomic arrangement is primarily determined by roughness build up at the film growth front, whereby larger roughness leads to increased intermixing between Ag and Au. These findings suggest a different structure formation pathway as compared to the immiscible Ag-Cu system for which the present study, in combination with previously published data, reveals that no significant roughness is developed, and the local atomic structure is predominantly determined by the tendency of Ag and Cu to phase-separate.

Place, publisher, year, edition, pages
New York: A I P Publishing LLC, 2018
National Category
Inorganic Chemistry Other Physics Topics Atom and Molecular Physics and Optics Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-147730 (URN)10.1063/1.5018907 (DOI)000431147200150 ()
Note

Funding agencies: Linkoping University via the "LiU Research Fellows Program"; Linkoping University via the "LiU Career Contract" [Dnr-LiU-2015-01510]; Swedish Research Council [VR-2011-5312, VR-2015-04630]

Available from: 2018-05-08 Created: 2018-05-08 Last updated: 2019-06-28Bibliographically approved
Elofsson, V., Almyras, G., Lu, B., Boyd, R. & Sarakinos, K. (2016). Atomic arrangement in immiscible Ag-Cu alloys synthesized far-from-equilibrium. Acta Materialia, 110, 114-121
Open this publication in new window or tab >>Atomic arrangement in immiscible Ag-Cu alloys synthesized far-from-equilibrium
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2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 110, p. 114-121Article in journal (Refereed) Published
Abstract [en]

Physical attributes of multicomponent materials of a given chemical composition are determined by atomic arrangement at property-relevant length scales. A potential route to access a vast array of atomic configurations for material property tuning is by synthesis of multicomponent thin films using vapor fluxes with their deposition pattern modulated in the sub-monolayer regime. However, the applicability of this route for creating new functional materials is impeded by the fact that a fundamental understanding of the combined effect of sub-monolayer flux modulation, kinetics and thermodynamics on atomic arrangement is not available in the literature. Here we present a research strategy and verify its viability for addressing the aforementioned gap in knowledge. This strategy encompasses thin film synthesis using a route that generates multi-atomic fluxes with sub-monolayer resolution and precision over a wide range of experimental conditions, deterministic growth simulations and nanoscale micro structural probes. Investigations are focused on structure formation within the archetype immiscible Ag-Cu binary system, revealing that atomic arrangement at different length scales is governed by the arrival pattern of the film forming species, in conjunction with diffusion of near-surface Ag atoms to encapsulate 3D Cu islands growing on 2D Ag layers. The knowledge generated and the methodology presented herein provides the scientific foundation for tailoring atomic arrangement and physical properties in a wide range of miscible and immiscible multinary systems. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2016
Keywords
Ag-Cu thin films; MD simulations; Modulated vapor fluxes; Nonequilibrium synthesis; Immiscible alloys
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-128722 (URN)10.1016/j.actamat.2016.03.023 (DOI)000374810400012 ()
Note

Funding Agencies|Linkoping University [Dnr-LiU-2015-01510]; Swedish Research Council [VR 621-2011-5312]; AForsk through the project "Towards Next Generation of Energy Saving Windows"

Available from: 2016-06-01 Created: 2016-05-30 Last updated: 2019-06-28
Sarakinos, K., Greczynski, G., Elofsson, V., Magnfält, D., Högberg, H. & Alling, B. (2016). Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system. Journal of Applied Physics, 119(9), 095303
Open this publication in new window or tab >>Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system
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2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 9, p. 095303-Article in journal (Refereed) Published
Abstract [en]

Metastable solid solutions are phases that are synthesized far from thermodynamic equilibrium and offer a versatile route to design materials with tailor-made functionalities. One of the most investigated classes of metastable solid solutions with widespread technological implications is vapor deposited ternary transition metal ceramic thin films (i.e., nitrides, carbides, and borides). The vapor-based synthesis of these ceramic phases involves complex and difficult to control chemical interactions of the vapor species with the growing film surface, which often makes the fundamental understanding of the composition-properties relations a challenging task. Hence, in the present study, we investigate the phase stability within an immiscible binary thin film system that offers a simpler synthesis chemistry, i.e., the Ag-Mo system. We employ magnetron co-sputtering to grow Ag1-xMox thin films over the entire composition range along with x-ray probes to investigate the films structure and bonding properties. Concurrently, we use density functional theory calculations to predict phase stability and determine the effect of chemical composition on the lattice volume and the electronic properties of Ag-Mo solid solutions. Our combined theoretical and experimental data show that Mo-rich films (x >= similar to 0.54) form bcc Mo-Ag metastable solid solutions. Furthermore, for Ag-rich compositions (x <= similar to 0.21), our data can be interpreted as Mo not being dissolved in the Ag fcc lattice. All in all, our data show an asymmetry with regards to the mutual solubility of Ag and Mo in the two crystal structures, i.e., Ag has a larger propensity for dissolving in the bcc-Mo lattice as compared to Mo in the fcc-Ag lattice. We explain these findings in light of isostructural short-range clustering that induces energy difference between the two (fcc and bcc) metastable phases. We also suggest that the phase stability can be explained by the larger atomic mobility of Ag atoms as compared to that of Mo. The mechanisms suggested herein may be of relevance for explaining phase stability data in a number of metastable alloys, such as ternary transition metal-aluminum-nitride systems. (C) 2016 AIP Publishing LLC.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-127275 (URN)10.1063/1.4942840 (DOI)000372351900057 ()
Note

Funding Agencies|Linkoping University [Dnr-LiU-2015-01510]; Swedish Research Council (VR) [621-2011-4417, 330-2014-6336]; VINN Excellence Center Functional Nanoscale Materials (FunMat); Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Available from: 2016-04-20 Created: 2016-04-19 Last updated: 2017-11-30Bibliographically approved
Sarakinos, K., Magnfält, D., Elofsson, V. & Lü, B. (2014). Atomistic view on thin film nucleation and growth by using highly ionized and pulsed vapour fluxes. Surface & Coatings Technology, 257, 326-332
Open this publication in new window or tab >>Atomistic view on thin film nucleation and growth by using highly ionized and pulsed vapour fluxes
2014 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 257, p. 326-332Article in journal (Refereed) Published
Abstract [en]

We present a brief review on the use of ionized and pulsed vapour fluxes, primarily generated by high power impulse magnetron sputtering (HiPIMS) discharges, as tools to gain atomistic understanding on film nucleation and growth. Two case studies are considered; the first case study concerns stress generation in polycrystalline films. It is highlighted that by using vapour fluxes of well-controlled ion content and ion energy and by studying the film microstructure and intrinsic stresses one can obtain experimental evidence for stress generation by insertion of film forming species in the grain boundaries. In the second case study it is discussed how the use of pulsed vapour fluxes with well controlled time domain can facilitate understanding of growth dynamics and microstructural evolution in thin films grown in three-dimensional (i.e., Volmer-Weber) fashion. Broader implications of the described research strategies for the surface science and surface engineering communities are highlighted and discussed.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Film nucleation and growth; In situ growth monitoring; Intrinsic stresses; Volmer-Weber film growth; HiPIMS; Microstructure
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112642 (URN)10.1016/j.surfcoat.2014.04.015 (DOI)000344423100032 ()
Note

Funding Agencies|Linkoping University through the "LiU Research Fellows" programme; Swedish Research Council [VR 621-2001-5312]; Angpanneforeningens Forskningsstiftelse through the project "Towards Next Generation Energy Saving Windows"

Available from: 2014-12-05 Created: 2014-12-05 Last updated: 2017-12-05Bibliographically approved
Elofsson, V., Saraiva, M., Boyd, R. & Sarakinos, K. (2014). Double in-plane alignment in biaxially textured thin films. Applied Physics Letters, 105(23), 233113
Open this publication in new window or tab >>Double in-plane alignment in biaxially textured thin films
2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 23, p. 233113-Article in journal (Refereed) Published
Abstract [en]

The scientific interest and technological relevance of biaxially textured polycrystalline thin films stem from their microstructure that resembles that of single crystals. To explain the origin and predict the type of biaxial texture in off-normally deposited films, Mahieu et al. have developed an analytical model [S. Mahieu et al., Thin Solid Films 515, 1229 (2006)]. For certain materials, this model predicts the occurrence of a double in-plane alignment, however, experimentally only a single in-plane alignment has been observed and the reason for this discrepancy is still unknown. The model calculates the resulting in-plane alignment by considering the growth of faceted grains with an out-of-plane orientation that corresponds to the predominant film out-of-plane texture. This approach overlooks the fact that in vapor condensation experiments where growth kinetics is limited and only surface diffusion is active, out-of-plane orientation selection is random during grain nucleation and happens only upon grain impingement. Here, we compile and implement an experiment that is consistent with the key assumptions set forth by the in-plane orientation selection model by Mahieu et al.; a Cr film is grown off-normally on a fiber textured Ti epilayer to pre-determine the out-of-plane orientation and only allow for competitive growth with respect to the in-plane alignment. Our results show unambiguously a biaxially textured Cr (110) film that possesses a double in-plane alignment, in agreement with predictions of the in-plane selection model. Thus, a long standing discrepancy in the literature is resolved, paving the way towards more accurate theoretical descriptions and hence knowledge-based control of microstructure evolution in biaxially textured thin films.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113499 (URN)10.1063/1.4903932 (DOI)000346266000086 ()
Note

Funding Agencies|Linkoping University

Available from: 2015-01-19 Created: 2015-01-19 Last updated: 2017-12-05
Lü, B., Elofsson, V., Münger, P. & Sarakinos, K. (2014). Dynamic competition between island growth and coalescence in metal-on-insulator deposition. Applied Physics Letters, 105(16), 163107-1-163107-5
Open this publication in new window or tab >>Dynamic competition between island growth and coalescence in metal-on-insulator deposition
2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 16, p. 163107-1-163107-5Article in journal (Refereed) Published
Abstract [en]

The morphology of thin metal films and nanostructures synthesized from the vapor phase on insulating substrates is strongly influenced by the coalescence of islands. Here, we derive analytically the quantitative criterion for coalescence suppression by combining atomistic nucleation theory and a classical model of coalescence. Growth simulations show that using this criterion, a coalescence-free growth regime can be reached in which morphological evolution is solely determined by island nucleation, growth, and impingement. Experimental validation for the ability to control the rate of coalescence using this criterion and navigate between different growth regimes is provided by in situ monitoring of Ag deposition on SiO2. Our findings pave the way for creating thin films and nanostructures that exhibit a wide range of morphologies and physical attributes in a knowledge-based manner.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112133 (URN)10.1063/1.4900575 (DOI)000344363000073 ()
Available from: 2014-11-17 Created: 2014-11-17 Last updated: 2018-01-11Bibliographically approved
Elofsson, V. (2014). Thin Film Growth using Pulsed and Highly Ionized Vapor Fluxes. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Thin Film Growth using Pulsed and Highly Ionized Vapor Fluxes
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Microstructure and morphology of thin films are decisive for many of their resulting properties. To be able to tailor these properties, and thus the film functionality, a fundamental understanding of thin film growth needs to be acquired. Film growth is commonly performed using continuous vapor fluxes with low energy, but additional handles to control growth can be obtained by instead using pulsed and energetic ion fluxes. In this licentiate thesis the physical processes that determine microstructure and morphology of thin films grown using pulsed and highly ionized vapor fluxes are investigated.

The underlying physics that determines the initial film growth stages (i.e., island nucleation, island growth and island coalescence) and how they can be manipulated individually when using pulsed vapor fluxes have previously been investigated. Their combined effect on film growth is, however, paramount to tailor film properties. In the thesis, a route to generate pulsed vapor fluxes using the vapor-based technique high power impulse magnetron sputtering (HiPIMS) is established. These fluxes are then used to grow Ag films on SiO2 substrates. For fluxes with constant energy and deposition rate per pulse it is demonstrated that the growth evolution is solely determined by the characteristics of the vapor flux, as set by the pulsing frequency, and the average time required for coalescence to be completed.

Highly ionized vapor fluxes have previously been used to manipulate film growth when deposition is performed both normal and off-normal to the substrate. For the latter case, the physical mechanisms that determine film microstructure and morphology are, however, not fully understood. Here it is shown that the tilted columnar microstructure obtained during  off-normal film growth is positioned closer to the substrate normal as the ionization degree of the flux increases, but only if certain nucleation characteristics are present.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. p. 53
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1641
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-103921 (URN)10.3384/lic.diva-103921 (DOI)978-91-7519-426-4 (ISBN)
Presentation
2014-02-28, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Note

The series name "Linköping studies in science and technology. Licentiate Thesis" is incorrect. The correct series name is "Linköping studies in science and technology. Thesis".

Available from: 2014-02-03 Created: 2014-02-03 Last updated: 2014-02-04Bibliographically approved
Elofsson, V., Magnfält, D., Münger, P. & Sarakinos, K. (2014). Unravelling the Physical Mechanisms that Determine Microstructural Evolution of Ultrathin Volmer-Weber Films. Journal of Applied Physics, 116(4), 044302
Open this publication in new window or tab >>Unravelling the Physical Mechanisms that Determine Microstructural Evolution of Ultrathin Volmer-Weber Films
2014 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 4, p. 044302-Article in journal (Refereed) Published
Abstract [en]

The initial formation stages (i.e., island nucleation, island growth, and island coalescence) set characteristic length scales during growth of thin films from the vapour phase. They are, thus, decisive for morphological and microstructural features of films and nanostructures. Each of the initial formation stages has previously been well-investigated separately for the case of Volmer-Weber growth, but knowledge on how and to what extent each stage individually and all together affect the microstructural evolution is still lacking. Here we address this question using growth of Ag on SiO2 from pulsed vapour fluxes as a case study. By combining in situ growth monitoring, ex situ imaging and growth simulations we systematically study the growth evolution all the way from nucleation to formation of a continuous film and establish the effect of the vapour flux time domain on the scaling behaviour of characteristic growth transitions (elongation transition, percolation and continuous film formation). Our data reveal a pulsing frequency dependence for the characteristic film growth transitions, where the nominal transition thickness decreases with increasing pulsing frequency up to a certain value after which a steady-state behaviour is observed. The scaling behaviour is shown to result from differences in island sizes and densities, as dictated by the initial film formation stages. These differences are determined solely by the interplay between the characteristics of the vapour flux and time required for island coalescence to be completed. In particular, our data provide evidence that the steady-state scaling regime of the characteristic growth transitions is caused by island growth that hinders coalescence from being completed, leading to a coalescence-free growth regime.

National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-103920 (URN)10.1063/1.4890522 (DOI)000340710700078 ()
Available from: 2014-02-03 Created: 2014-02-03 Last updated: 2018-01-11
Elofsson, V., Magnfält, D., Samuelsson, M. & Sarakinos, K. (2013). Tilt of the columnar microstructure in off-normally deposited thin films using highly ionized vapor fluxes. Journal of Applied Physics, 113(17), 7 pages
Open this publication in new window or tab >>Tilt of the columnar microstructure in off-normally deposited thin films using highly ionized vapor fluxes
2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 17, p. 7 pages-Article in journal (Refereed) Published
Abstract [en]

The tilt of the columnar microstructure has been studied for Cu and Cr thin films grown off-normally using highly ionized vapor fluxes, generated by the deposition technique high power impulse magnetron sputtering. It is found that the relatively large column tilt (with respect to the substrate normal) observed for Cu films decreases as the ionization degree of the deposition flux increases. On the contrary, Cr columns are found to grow relatively close to the substrate normal and the column tilt is independent from the ionization degree of the vapor flux when films are deposited at room temperature. The Cr column tilt is only found to be influenced by the ionized fluxes when films are grown at elevated temperatures, suggesting that film morphology during the film nucleation stage is also important in affecting column tilt. A phenomenological model that accounts for the effect of atomic shadowing at different nucleation conditions is suggested to explain the results.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-94608 (URN)10.1063/1.4804066 (DOI)000319292800398 ()
Available from: 2013-06-27 Created: 2013-06-27 Last updated: 2017-12-06Bibliographically approved
Magnfält, D., Elofsson, V., Abadias, G., Helmersson, U. & Sarakinos, K. (2013). Time-domain and energetic bombardment effects on the nucleation and coalescence of thin metal films on amorphous substrates. Journal of Physics D: Applied Physics, 46(21), Article ID 215303.
Open this publication in new window or tab >>Time-domain and energetic bombardment effects on the nucleation and coalescence of thin metal films on amorphous substrates
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2013 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 46, no 21, article id 215303Article in journal (Refereed) Published
Abstract [en]

Pulsed, ionized vapour fluxes, generated from high power impulse magnetron sputtering (HiPIMS) discharges, are employed to study the effects of time-domain and energetic bombardment on the nucleation and coalescence characteristics during Volmer–Weber growth of metal (Ag) films on amorphous (SiO2) substrates. In situ monitoring of the film growth, by means of wafer curvature measurements and spectroscopic ellipsometry, is used to determine the film thickness where a continuous film is formed. This thickness decreases from ~210 to ~140 Å when increasing the pulsing frequency for a constant amount of material deposited per pulse or when increasing the amount of material deposited per pulse and the energy of the film forming species for a constant pulsing frequency. Estimations of adatom lifetimes and the coalescence times show that there are conditions at which these times are within the range of the modulation of the vapour flux. Thus, nucleation and coalescence processes can be manipulated by changing the temporal profile of the vapour flux. We suggest that other than for elucidating the atomistic mechanisms that control pulsed growth processes, the interplay between the time scales for diffusion, coalescence and vapour flux pulsing can be used as a tool to determine characteristic surface diffusion and island coalescence parameters.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-95508 (URN)10.1088/0022-3727/46/21/215303 (DOI)000319116300009 ()
Note

Funding Agencies|Swedish Research Council|VR 621-2011-4280|COST Action Highly Ionized Pulsed Plasmas|MP0804|Linkoping University via the LiU Research Fellows program||.

The previous status of the article was Manuscript and the working title was Time-domain and energetic bombardment effects on the nucleation and post-nucleation characteristics during none-quilibrium film synthesis.

Available from: 2013-07-05 Created: 2013-07-05 Last updated: 2017-12-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4811-478X

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