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Ghamgosar, P., Rigoni, F., Gilzad Kohan, M., You, S., Morales, E. A., Mazzaro, R., . . . Vomiero, A. (2019). Self-Powered Photodetectors Based on Core-Shell ZnO-Co3O4 Nanowire Heterojunctions. ACS Applied Materials and Interfaces, 11(26), 23454-23462
Open this publication in new window or tab >>Self-Powered Photodetectors Based on Core-Shell ZnO-Co3O4 Nanowire Heterojunctions
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 26, p. 23454-23462Article in journal (Refereed) Published
Abstract [en]

Self-powered photodetectors operating in the UV–visible–NIR window made of environmentally friendly, earth abundant, and cheap materials are appealing systems to exploit natural solar radiation without external power sources. In this study, we propose a new p–n junction nanostructure, based on a ZnO–Co3O4 core–shell nanowire (NW) system, with a suitable electronic band structure and improved light absorption, charge transport, and charge collection, to build an efficient UV–visible–NIR p–n heterojunction photodetector. Ultrathin Co3O4 films (in the range 1–15 nm) were sputter-deposited on hydrothermally grown ZnO NW arrays. The effect of a thin layer of the Al2O3 buffer layer between ZnO and Co3O4 was investigated, which may inhibit charge recombination, boosting device performance. The photoresponse of the ZnO–Al2O3–Co3O4 system at zero bias is 6 times higher compared to that of ZnO–Co3O4. The responsivity (R) and specific detectivity (D*) of the best device were 21.80 mA W–1and 4.12 × 1012 Jones, respectively. These results suggest a novel p–n junction structure to develop all-oxide UV–vis photodetectors based on stable, nontoxic, low-cost materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
ZnO−CoO core−shell, all-oxide p−n heterojunction, nanowire geometry, photovoltaic photodetector, self-powered photodetector
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75216 (URN)10.1021/acsami.9b04838 (DOI)000474670100061 ()31252456 (PubMedID)2-s2.0-85068447779 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-04 (svasva)

Available from: 2019-07-04 Created: 2019-07-04 Last updated: 2019-08-30Bibliographically approved
de Melo, C., Jullien, M., Battie, Y., Naciri, A. E., Ghanbaja, J., Montaigne, F., . . . Horwat, D. (2019). Semi-Transparent p‑Cu2O/n-ZnO Nanoscale-Film Heterojunctions for Photodetection and Photovoltaic Applications. ACS Applied Nano Materials, 2(7), 4358-4366
Open this publication in new window or tab >>Semi-Transparent p‑Cu2O/n-ZnO Nanoscale-Film Heterojunctions for Photodetection and Photovoltaic Applications
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2019 (English)In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 2, no 7, p. 4358-4366Article in journal (Refereed) Published
Abstract [en]

Transparent nanoscale-film heterojunctions based on Cu2O and ZnO were fabricated by atomic layer deposition and reactive magnetron sputtering. The constitutive layers exhibit high crystalline quality and a local epitaxial relation between Cu2O and ZnO was achieved with [110] Cu2O || [001] ZnO and [001] Cu2O || [010] ZnO as evidenced by high resolution transmission electron microscopy and. Cu2O films show very low resistivity and high mobility values of 9–150 Ω cm and 19 cm2/V s, respectively. The Cu2O/ZnO heterojunctions exhibit a nonlinear rectifying behavior characteristic of a p–n junction, self-powered photoresponse under 1 Sun illumination and an average transmittance of 73% in the visible region of the electromagnetic spectrum. These results are promising for all-oxide transparent electronics, photodetection and photovoltaic applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
copper oxide, atomic layer deposition, local epitaxy, heterojunction, transparent electronics, photodetectors
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75600 (URN)10.1021/acsanm.9b00808 (DOI)000477917700037 ()2-s2.0-85068417554 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-08-20 (johcin)

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-08-20Bibliographically approved
De Melo, C., Jullien, M., Ghanbaja, J., Montaigne, F., Pierson, J.-F., Soldera, F., . . . Horwat, D. (2018). Local Structure and Point-Defect-Dependent Area-Selective Atomic Layer Deposition Approach for Facile Synthesis of p-Cu2O/n-ZnO Segmented Nanojunctions. ACS Applied Materials and Interfaces, 10(43), 37671-37678
Open this publication in new window or tab >>Local Structure and Point-Defect-Dependent Area-Selective Atomic Layer Deposition Approach for Facile Synthesis of p-Cu2O/n-ZnO Segmented Nanojunctions
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 43, p. 37671-37678Article in journal (Refereed) Published
Abstract [en]

Area-selective atomic layer deposition (AS-ALD) has attracted much attention in recent years due to the possibility of achieving accurate patterns in nanoscale features, which render this technique compatible with the continuous downscaling in nanoelectronic devices. The growth selectivity is achieved by starting from different materials and results (ideally) in localized growth of a single material. We propose here a new concept, more subtle and general, in which a property of the substrate is modulated to achieve localized growth of different materials. This concept is demonstrated by selective growth of high-quality metallic Cu and semiconducting Cu2O thin films, achieved by changing the type of majority point defects in the ZnO underneath film exposed to the reactive species using a patterned bilayer structure composed of highly conductive and highly resistive areas, as confirmed by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The selective growth of these materials in a patterned ZnO/Al-doped ZnO substrate allows the fabrication of p-Cu2O/n-ZnO nanojunctions showing a nonlinear rectifying behavior typical of a p-n junction, as confirmed by conductive atomic force microscopy (C-AFM). This process expands the spectra of materials that can be grown in a selective manner by ALD and opens up the possibility of fabricating different architectures, taking advantage of the area-selective deposition. This offers a variety of opportunities in the field of transparent electronics, catalysis, and photovoltaics.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
area-selective deposition, atomic layer deposition, patterning, p−n junctions, transmission electron microscopy
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-71408 (URN)10.1021/acsami.8b12584 (DOI)000449239600118 ()30261135 (PubMedID)2-s2.0-85055202959 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-05 (johcin)

Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2019-03-27Bibliographically approved
de Melo, C., Jullien, M., Battie, Y., En Naciri, A., Ghanbaja, J., Montaigne, F., . . . Horwat, D. (2018). Tunable Localized Surface Plasmon Resonance and Broadband Visible Photoresponse of Cu Nanoparticles/ZnO Surfaces. ACS Applied Materials and Interfaces, 10(47), 40958-40965
Open this publication in new window or tab >>Tunable Localized Surface Plasmon Resonance and Broadband Visible Photoresponse of Cu Nanoparticles/ZnO Surfaces
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 47, p. 40958-40965Article in journal (Refereed) Published
Abstract [en]

Plasmonic Cu nanoparticles (NP) were successfully deposited on ZnO substrates by atomic layer deposition (ALD) owing to the Volmer–Weber island growth mode. An evolution from Cu NP to continuous Cu films was observed with an increasing number of ALD cycles. Real and imaginary parts of the NP dielectric functions, determined by spectroscopic ellipsometry using an effective medium approach, evidence a localized surface plasmon resonance that can be tuned between the visible and near-infrared ranges by controlling the interparticle spacing and size of the NP. The resulting Cu NP/ZnO device shows an enhanced photoresponse under white light illumination with good responsivity values, fast response times, and stability under dark/light cycles. The significant photocurrent detected for this device is related to the hot-electron generation at the NP surface and injection into the conduction band of ZnO. The possibility of tuning the plasmon resonance together with the photoresponsivity of the device is promising in many applications related to photodetection, photonics, and photovoltaics.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
atomic layer deposition, copper nanoparticles, hot electrons, localized surface plasmon resonance, photodetectors
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-71637 (URN)10.1021/acsami.8b17194 (DOI)000451932800064 ()30398332 (PubMedID)2-s2.0-85056897869 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-04 (inah)

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2019-09-13Bibliographically approved
Ghamgosar, P., Rigoni, F., You, S., Dobryden, I., Gilzad Kohan, M., Pellegrino, A. L., . . . Vomiero, A. (2018). ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors. Nano Energy, 51, 308-316
Open this publication in new window or tab >>ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 51, p. 308-316Article in journal (Refereed) Published
Abstract [en]

In this work, we present all-oxide p-n junction core-shell nanowires (NWs) as fast and stable self-powered photodetectors. Hydrothermally grown n-type ZnO NWs were conformal covered by different thicknesses (up to 420 nm) of p-type copper oxide layers through metalorganic chemical vapor deposition (MOCVD). The ZnO NWs exhibit a single crystalline Wurtzite structure, preferentially grown along the [002] direction, and energy gap Eg=3.24 eV. Depending on the deposition temperature, the copper oxide shell exhibits either a crystalline cubic structure of pure Cu2O phase (MOCVD at 250 °C) or a cubic structure of Cu2O with the presence of CuO phase impurities (MOCVD at 300 °C), with energy gap of 2.48 eV. The electrical measurements indicate the formation of a p-n junction after the deposition of the copper oxide layer. The core-shell photodetectors present a photoresponsivity at 0 V bias voltage up to 7.7 µA/W and time response ≤0.09 s, the fastest ever reported for oxide photodetectors in the visible range, and among the fastest including photodetectors with response limited to the UV region. The bare ZnO NWs have slow photoresponsivity, without recovery after the end of photo-stimulation. The fast time response for the core-shell structures is due to the presence of the p-n junctions, which enables fast exciton separation and charge extraction. Additionally, the suitable electronic structure of the ZnO-Cu2O heterojunction enables self-powering of the device at 0 V bias voltage. These results represent a significant advancement in the development of low-cost, high efficiency and self-powered photodetectors, highlighting the need of fine tuning the morphology, composition and electronic properties of p-n junctions to maximize device performances.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-69838 (URN)10.1016/j.nanoen.2018.06.058 (DOI)000440682100034 ()2-s2.0-85049324019 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-02 (rokbeg)

Available from: 2018-06-25 Created: 2018-06-25 Last updated: 2019-04-19Bibliographically approved
Sefer, B., Dobryden, I., Almqvist, N., Pederson, R. & Antti, M.-L. (2017). Chemical Milling of Cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo Alloys in Hydrofluoric-Nitric Acid Solutions. Corrosion, 73(4), 394-407
Open this publication in new window or tab >>Chemical Milling of Cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo Alloys in Hydrofluoric-Nitric Acid Solutions
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2017 (English)In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 4, p. 394-407Article in journal (Refereed) Published
Abstract [en]

The behavior of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo during chemical milling in hydrofluoric-nitric (HF-HNO3) acid solutions with 1:3 and 1:11 molar ratios was investigated using electrochemical and atomic force microscopy (AFM) techniques. Faster corrosion rate in 1:3 solutions was measured for Ti-6Al-4V than for Ti-6Al-2Sn-4Zr-2Mo, whereas in 1:11 solution Ti-6Al-2Sn-4Zr-2Mo exhibited higher corrosion rate. Scanning Kelvin probe force microscopy measurements revealed difference in the Volta potential between the α-laths and the β-layers in the Widmansttäten microstructure indicating operation of microgalvanic cells between the microconstituents when in contact with HF-HNO3 solution. The AFM topography measurements demonstrated faster corrosion of the α-laths compared to the β-layers, in both alloys. In 1:3 solutions, higher α/β height difference was measured in Ti-6Al-4V, whereas in 1:11 solution, the difference was higher in Ti-6Al-2Sn-4Zr-2Mo. The results revealed that the chemical milling behavior of the two investigated alloys is controlled by the microscopic corrosion behavior of the individual microconstituents.

Place, publisher, year, edition, pages
NACE International, 2017
Keywords
atomic force microscopy, chemical milling/pickling, galvanic corrosion, linear polarization resistance, scanning Kelvin probe force microscopy, titanium alloys
National Category
Other Materials Engineering Other Physics Topics
Research subject
Engineering Materials; Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-62982 (URN)10.5006/2277 (DOI)000397433600008 ()2-s2.0-85020742117 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-04-11 (rokbeg)

Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2018-12-14Bibliographically approved
Dobryden, I., Touati, B., Gassoumi, A., Vomiero, A., Kamoun, N. & Almqvist, N. (2017). Morphological and electrical characterization of Cu-doped PbS thin films with AFM. Advanced Materials Letters, 8(11), 1029-1037
Open this publication in new window or tab >>Morphological and electrical characterization of Cu-doped PbS thin films with AFM
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2017 (English)In: Advanced Materials Letters, ISSN 0976-3961, E-ISSN 0976-397X, Vol. 8, no 11, p. 1029-1037Article in journal (Refereed) Published
Abstract [en]

Lead sulphide (PbS) is a direct band gap IV–VI intrinsic p-type semiconductor with good potential for application in solar cells, sensors, etc. Doping the films with Cu2+ ions may improve the electrical properties. Here, Cu-doped PbS films were deposited on conducting glass substrates. The morphology, topography and thickness of the doped PbS films were examined using atomic force microscopy (AFM) and high-resolution SEM. AFM analysis showed decreasing surface roughness and grain size with the increase of Cu2+ concentration from 0.5 to 2.0 at%. Local surface electrical measurements using conducting AFM and Kelvin probe force microscopy showed the possibility to probe semi-quantitatively the changes in surface potential, work function, and Fermi level upon doping of the films. The estimated apparent work function for the un-doped PbS grains in the film was slightly above 4.5 eV, while it decreased to a minimum value of 4.43-4.45 eV at 1–1.5 at% Cu-doping. Conducting AFM measurements showed that local resistance of the doped samples is lower than on pure PbS films. These results indicate Cu doping as an effective strategy to tune the electrical properties of PbS thin films toward the development of suitable optically active materials for application in photovoltaics.

Place, publisher, year, edition, pages
VBRI Press, 2017
Keywords
Lead sulphide, KPFM, copper ions, solar cell, thin film
National Category
Nano Technology Other Physics Topics
Research subject
Experimental physics
Identifiers
urn:nbn:se:ltu:diva-65415 (URN)10.5185/amlett.2017.1545 (DOI)
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2018-04-26Bibliographically approved
Jirlèn, J., Concina, I., Lundström, I. & Almqvist, N. (2017). Towards nanolithography with starch and α-amylase: Invited lecture. In: Proceedings and Abstracts Book of European Advanced Materials Congress 2017: . Paper presented at European Advanced Materials Congress (EAMC-17), Stockholm, Sweden, 22-24 August 2017.
Open this publication in new window or tab >>Towards nanolithography with starch and α-amylase: Invited lecture
2017 (English)In: Proceedings and Abstracts Book of European Advanced Materials Congress 2017, 2017Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Nanotechnology using enzyme technology to modify surfaces on the nanometer scale and nanostructuring surfaces is an evolving research field. One of the advantages with enzyme assisted nanolithography is the high substrate specificity. Scanning probe microscopy (SPM) in liquid or ambient conditions is highly suited for such nanolithography: we are in particular using atomic force microscopy (AFM) to develop negative nanolithography based on an enzyme and its substrate. The possibility of high accuracy positioning of the SPM probe tip is combined with the activity of an enzyme. There are very few related such studies by other groups [1-3]. In our approach, the enzyme is α-amylase and the substrate starch, whose hydrolysis into sugars by α-amylase is well studied on the macro-scale. The system α-amylase-starch is exploited as a model to demonstrate the proof of principle that the enzyme can be used with SPM methods to locally degrade starch and ultimately write nanopatterns on starch surfaces. Silicon surfaces are covered with smooth and thin layers of starch, whose roughness, morphology and nanomechanical properties are characterized by AFM methods. In the next step the degradation of these starch layers will be demonstrated with an AFM tip functionalized with amylase molecules, either on the apex of a “sharp” AFM tip (outer radius 5-50 nm) or on a micrometer-sized bead of silicon dioxide glued to an AFM cantilever. The α-amylase molecules may be either spontaneously adsorbed or covalently attached to the tip through established functionalization chemistry. Results will be presented related to the structure and quality of the starch layer and its degradation by amylase in solution as observed by AFM and FTIR-spectroscopy and to the activity of amylase immobilized on (silicon/silicon dioxide) surfaces. Preliminary results will be given on the local degradation of starch caused by AFM tips modified by α-amylase and/or by micro droplets of amylase solution released on the substrate by using the AFM tip in a dip-pen configuration. The ultimate goal is to achieve a situation like that illustrated in the drawing above, where a single (or few) α-amylase molecule(s) is attached on the AFM tip so to maintain its enzymatic activity and can be used to write nanopatterns in a layer of starch.

Keywords
Enzyme, Nanolithography, Starch, Scanning probe microscopy
National Category
Nano Technology
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-65417 (URN)10.5185/eamc.2017 (DOI)978-91-88252-06-7 (ISBN)
Conference
European Advanced Materials Congress (EAMC-17), Stockholm, Sweden, 22-24 August 2017
Available from: 2017-08-30 Created: 2017-08-30 Last updated: 2019-09-13Bibliographically approved
Touati, B., Dobryden, I., Salem, Y. ., Gassoumi, A., Natile, M. M., Vomiero, A., . . . Kamoun, N. (2016). Morphological and electrical characterization of Cu-doped PbS thin films (ed.). In: (Ed.), : . Paper presented at Euroropean Advanced Materials Congress : 23/08/2016 - 25/08/2016.
Open this publication in new window or tab >>Morphological and electrical characterization of Cu-doped PbS thin films
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2016 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Lead sulphide (PbS) thin films represent a direct band gap IV–VI p-type semiconductor material (Eg= 0.41 eV) and have a good potential application in solar cells, infrared detector devices, sensors, etc[1]. The electrical properties of PbS film can be tuned via doping with Cu2+ and Cd2+[2, 3]. These ions have good ability to substitute Pb2+ locations in the PbS crystal lattice, and thus tune its energy band gap. Also, the structural properties of the film, such as the grain size, can depend on the dopant concentration and will affect the PbS band gap and conductivity. These features are important for instance, when PbS film are applied as photoactive materials in solar cells[4]. Here we present an investigation on doping PbS thin films by Cu. Cu-doped PbS films were deposited on ordinary glass and conducting glass substrates through chemical bath deposition. The samples deposited on the F:SnO2 conducting layers were used for a high-resolution SEM measurements and scanning spreading resistance microscopy (SSRM) characterization using scanning probe microscopy (SPM). The morphology and topography of the doped PbS films were examined using tapping mode AFM (NT-MDT Ntegra) and high-resolution SEM (Magellan 400 XHR-SEM). The crystalline shape was triangular and did not change much with the dopant concentration increase from 0.5% to 2%. Films in the range 120 to 380 nm were considered. Good agreement was found between thickness measured through cross-section HR-SEM and Rutherford backscattering spectrometry (RBS). Also, the RBS investigation has shown that the film thickness tends to decrease for an increase of the dopant concentration. All the doped films seem having lower doping concentration, compared to the nominal one, as obtained from RBS analysis. XPS highlighted a Cu-enriched surface layer, possibly due to selective segregation of the doped films during their growth. Additionally, advanced electrical measurements using SSRM and Kelvin probe force microscopy (KPFM) are underway. The possibility of tuning both the electrical and optical properties of PbS thin films by doping represents a viable strategy for the development of suitable optically active materials for application in photovoltaics.

National Category
Other Physics Topics
Research subject
Fysik; Experimental physics
Identifiers
urn:nbn:se:ltu:diva-37678 (URN)10.5185/eamc2016 (DOI)bc594165-93a9-4ba8-9024-9f1d40e89937 (Local ID)bc594165-93a9-4ba8-9024-9f1d40e89937 (Archive number)bc594165-93a9-4ba8-9024-9f1d40e89937 (OAI)
Conference
Euroropean Advanced Materials Congress : 23/08/2016 - 25/08/2016
Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-04-26Bibliographically approved
Nordlund, M., Bhandary, S., Sanyal, B., Almqvist, N., Löfqvist, T. & Grennberg, H. (2016). Side-selective self-assembly of graphene and FLG on piezoelectric PVDF from suspension (ed.). Paper presented at . Journal of Physics D: Applied Physics, 49(7), Article ID 07LT01.
Open this publication in new window or tab >>Side-selective self-assembly of graphene and FLG on piezoelectric PVDF from suspension
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2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 7, article id 07LT01Article in journal (Refereed) Published
Abstract [en]

The deposition of few-layer graphene by self-assembly from suspension onto a piezoelectric polymer substrate is presented. The graphene self-assembles with negligible overlap between flakes, and with high selectivity for one of the faces of the substrate, an observation which is discussed and rationalized. A computational study on a model system further confirms the theory and supports the experimental results. The highest obtained degree of surface coverage was estimated to 77%

National Category
Other Physics Topics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Experimental physics; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-12657 (URN)10.1088/0022-3727/49/7/07LT01 (DOI)000369403700001 ()2-s2.0-84957599945 (Scopus ID)bd171426-9d23-4dac-a405-bf9941156e93 (Local ID)bd171426-9d23-4dac-a405-bf9941156e93 (Archive number)bd171426-9d23-4dac-a405-bf9941156e93 (OAI)
Note
Validerad; 2016; Nivå 2; 20160219 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1646-569x

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