Snorre Braathen Kjeldby

• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Zeng, L. J.; Azarov, A.; Pokle, A. & Nguyen, P.D. [Show all 10 contributors for this article] (2024). In situ atomic-resolution study of transformations in double polymorph γ/β-Ga2O3 structures. Materials Advances. ISSN 2633-5409. 5, p. 3824–3831. doi: 10.1039/D3MA01011B. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Selnesaunet, Gard Momrak; Enga, Marius; Kjeldby, Snorre Braathen; Müting, Johanna & Vines, Lasse [Show all 7 contributors for this article] (2023). Charge State Control Over Point Defects in SiC Devices. Defect and Diffusion Forum. ISSN 1012-0386. 425, p. 35–42. doi: 10.4028/p-6ho92o. Full text in Research Archive
• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; García Fernández, Javier; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Show all 9 contributors for this article] (2023). Optical properties of ZnFe2O4 nanoparticles and Fe-decorated inversion domain boundaries in ZnO. Nanoscale Advances. 5(7), p. 2102–2110. doi: 10.1039/d2na00849a. Full text in Research Archive Show summary

  The maximum efficiency of solar cells utilizing a single layer for photovoltaic conversion is given by the single junction Shockley–Queisser limit. In tandem solar cells, a stack of materials with different band gaps contribute to the conversion, enabling tandem cells to exceed the single junction Shockley–Queisser limit. An intriguing variant of this approach is to embed semiconducting nanoparticles in a transparent conducting oxide (TCO) solar cell front contact. This alternative route would enhance the functionality of the TCO layer, allowing it to participate directly in photovoltaic conversion via photon absorption and charge carrier generation in the nanoparticles. Here, we demonstrate the functionalization of ZnO through incorporation of either ZnFe2O4 spinel nanoparticles (NPs) or inversion domain boundaries (IDBs) decorated by Fe. Diffuse reflectance spectroscopy and electron energy loss spectroscopy show that samples containing spinel particles and samples containing IDBs decorated by Fe both display enhanced absorption in the visible range at around 2.0 and 2.6 eV. This striking functional similarity was attributed to the local structural similarity around Fe-ions in spinel ZnFe2O4 and at Fe-decorated basal IDBs. Hence, functional properties of the ZnFe2O4 arise already for the two-dimensional basal IDBs, from which these planar defects behave like two-dimensional spinel-like inclusions in ZnO. Cathodoluminescence spectra reveal an increased luminescence around the band edge of spinel ZnFe2O4 when measuring on the spinel ZnFe2O4 NPs embedded in ZnO, whereas spectra from Fe-decorated IDBs could be deconvoluted into luminescence contributions from bulk ZnO and bulk ZnFe2O4.

• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Karlsen, Ole Bjørn; Vines, Lasse & Prytz, Øystein (2022). Formation of γ-Ga2O3 by ion implantation: Polymorphic phase transformation of β-Ga2O3. Applied Physics Letters. ISSN 0003-6951. 121(19). doi: 10.1063/5.0120103. Full text in Research Archive
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Venkatachalapathy, Vishnukanthan; Mikšová, R. & MacKová, A. [Show all 9 contributors for this article] (2022). Radiation-induced defect accumulation and annealing in Si-implanted gallium oxide. Journal of Applied Physics. ISSN 0021-8979. 131(12). doi: 10.1063/5.0083858. Full text in Research Archive
• Milenko, Karolina Barbara; Fuglerud, Silje Skeide; Kjeldby, Snorre Braathen; Ellingsen, Reinold; Aksnes, Astrid & Hjelme, Dag Roar (2018). Micro-lensed optical fibers for a surface-enhanced Raman scattering sensing probe. Optics Letters. ISSN 0146-9592. 43(24), p. 6029–6032. doi: 10.1364/OL.43.006029. Full text in Research Archive Show summary

  We present the fabrication and characterization of a novel sensing configuration based on surface-enhanced Raman scattering (SERS) and two micro-lensed optical fibers. The first micro-lensed fiber is used to excite surface plasmon resonance in a gold film deposited over a mono-layer of nano-sphere surface (AuFON), and the second lensed fiber is used to collect the SERS signal. The sensing capabilities of the fabricated device are demonstrated by measuring different concentrations of Rhodamine 6G in a water solution.

• Kjeldby, Snorre Braathen; Evenstad, Otto Magnus; Cooil, Simon Phillip & Wells, Justin (2017). Probing dimensionality using a simplified 4-probe method. Journal of Physics: Condensed Matter. ISSN 0953-8984. 29(39). doi: 10.1088/1361-648X/aa8296.

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• Kjeldby, Snorre Braathen; García Fernández, Javier; Nguyen, Phuong Dan; Prytz, Øystein & Vines, Lasse (2023). Implantation for polymorphic transformation in Ga2O3: thermal evolution and luminescence. Show summary

  Dette foredraget presenterer ioneimplantasjonindusert fasetransformasjon i galliumoksid, Ga2O3, fra beta-fasen til gamma-fasen. Den siste tiden har det vært utbredt vitenskaplig interesse i denne transformasjonen, som, basert på tilgjengelige data, ser ut til å være uavhengig av det implanterte speciet. Utover å presentere forsøk som fastslår den termiske stabiliteten til gamma-fasen, opp til 500 eller 700 grader Celsius avhengig av implantasjonsparametre, presenterer vi her også de første luminesensmålingene på slike prøver med høy romlig oppløsning, hovedsaklig fra prøver implantert med germanium, med støttende resultater fra nikkelimplanterte prøver. Både intrinsisk luminesens, fra selvlokaliserte hull og intrinsiske defekter, og ekstrinsisk luminesens fra krom ble studert. Foredraget bidrar til å klargjøre ikke bare strukturen men også egenskapene til fasetransformerte lag i galliumoksid fra ioneimplantasjon.

• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Show all 9 contributors for this article] (2023). Optical properties and structure relationship in ZnO:Fe with inversion domain boundaries and ZnFe2O4/ZnO heterostructures.
• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Azarov, Alexander; Pokle, Anuj; Nguyen, Phuong Dan & Vines, Lasse [Show all 8 contributors for this article] (2023). Polymorph engineering and radiation tolerance in β-Ga2O3.
• Bathen, Marianne Etzelmüller; Enga, Marius Johan; Selnesaunet, Gard Momrak; Kjeldby, Snorre Braathen; Galeckas, Augustinas & Müting, Johanna [Show all 8 contributors for this article] (2022). Charge state control over point defects in SiC devices.
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Garcia Fernandez, Javier; Venkatachalapathy, Vishnukanthan & Mikšová, Romana [Show all 10 contributors for this article] (2022). Structure and luminescence properties of Si-implanted β-Ga2O3.
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Venkatachalapathy, Vishnukanthan; Mikšová, Romana & Macková, Anna [Show all 10 contributors for this article] (2022). Structural Transformation of β-Ga2O3 through Si-implantation.
• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Garcia Fernandez, Javier; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Show all 9 contributors for this article] (2022). Optical properties of Fe-decorated inversion domain boundaries and embedded spinel zinc ferrite nanoparticles in zinc oxide.
• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Show all 9 contributors for this article] (2022). Structural and optical investigation of Fe-ZnO nanoarchitectures: from inversion domain boundaries to ZnO/ZnFe2O4 heterostructure.
• Elgvin, Cana; Kjeldby, Snorre Braathen; Both, Kevin Gregor; Nguyen, Phuong Dan & Prytz, Øystein (2022). Optical Properties of Zinc Ferrite Nanoparticles Embedded in Zinc Oxide Thin Films Investigated by STEM, EELS and CL.
• Olsen, Vegard Skiftestad; Hommedal, Ylva Knausgård; Kjeldby, Snorre Braathen & Karlsen, Kjetil (2021). Omvisning UiO MiNaLab for Tekna representanter.
• Olsen, Vegard Skiftestad; Kjeldby, Snorre Braathen; Karlsen, Kjetil & Knausgård Hommedal, Ylva (2021). Omvisning UiO MiNaLab for MENA bachelorstudenter.
• Kjeldby, Snorre Braathen; Azarov, Alexander; Aarholt, Thomas; Prytz, Øystein & Vines, Lasse (2021). Defect-annealing in Si+-implanted β-Ga2O3.
• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas; Jensen, Ingvild Julie Thue & Thøgersen, Annett [Show all 8 contributors for this article] (2021). EELS and SEM-CL investigations of ZnFe2O4 nanoparticles and iron-decorated inversion domain boundaries in bulk ZnO.
• Pedersen, Benedicte Allum; Vines, Lasse; Kjeldby, Snorre Braathen & Reinertsen, Vilde Mari (2022). Positioning and control of single-photon emitters in SiC-based nanostructures for quantum applications. Universitetet i Oslo.

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