Kristin Bergum

• Saxegaard, Kjetil Karlsen; Monakhov, Eduard; Vines, Lasse & Bergum, Kristin (2023). Characteristics of ZnON films and heterojunction diodes with varying O:N ratios. Thin Solid Films. ISSN 0040-6090. 782. doi: 10.1016/j.tsf.2023.139968. Fulltekst i vitenarkiv
• Nayak, Mrutyunjay; Bergum, Kristin; Stan, George E.; Lee, In-Hwan & Kuznetsov, Andrej (2023). Sub-Stochiometric Nickel Oxide Hole-Selective Contacts in Solar Cells: Comparison of Simulations and Experiments with Sputtered Films. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 220(10), s. 1–7. doi: 10.1002/pssa.202200651. Fulltekst i vitenarkiv
• Nyborg, Martin; Karlsen, Kjetil; Bergum, Kristin & Monakhov, Eduard (2021). Dominant acceptors in Li doped, magnetron deposited Cu2O films. Materials Research Express. ISSN 2053-1591. 8(12), s. 1–8. doi: 10.1088/2053-1591/ac3e24. Fulltekst i vitenarkiv
• Nyborg, Martin; Kolevatov, Ilia; Vasquez, Geraldo Cristian; Bergum, K. & Monakhov, E. (2021). Dominant defects and carrier transport in single crystalline cuprous oxide: A new attribution of optical transitions. Journal of Applied Physics. ISSN 0021-8979. 130(17). doi: 10.1063/5.0059406. Fulltekst i vitenarkiv
• Nyborg, Martin; Azarov, Alexander; Bergum, Kristin & Monakhov, Eduard (2021). Deposition and characterization of lithium doped direct current magnetron sputtered Cu2O films. Thin Solid Films. ISSN 0040-6090. 722(31), s. 1–5. doi: 10.1016/j.tsf.2021.138573. Fulltekst i vitenarkiv
• Kumar, Raj; Bergum, Kristin; Riise, Heine Nygard; Monakhov, Eduard; Galeckas, Augustinas & Svensson, Bengt Gunnar (2020). Impact of post annealing and hydrogen implantation on functional properties of Cu2O thin films for photovoltaic applications. Journal of Alloys and Compounds. ISSN 0925-8388. 825(5), s. 1–8. doi: 10.1016/j.jallcom.2020.153982. Fulltekst i vitenarkiv
• Nordseth, Ørnulf; Kumar, Raj; Bergum, Kristin; Chilibon, Irinela; Foss, Sean Erik & Monakhov, Eduard (2019). Nitrogen-Doped Cu2O Thin Films for Photovoltaic Applications. Materials. ISSN 1996-1944. 12(18). doi: 10.3390/ma12183038. Fulltekst i vitenarkiv
• Nordseth, Ørnulf; Kumar, Raj; Bergum, Kristin; Fara, Laurentiu; Dumitru, Constantin & Craciunescu, Dan [Vis alle 11 forfattere av denne artikkelen] (2018). Metal oxide thin-film heterojunctions for photovoltaic applications. Materials. ISSN 1996-1944. 11(12), s. 1–10. doi: 10.3390/ma11122593. Fulltekst i vitenarkiv
• Bergum, Kristin; Riise, Heine Nygard; Gorantla, Sandeep Madhukar; Lindberg, Per; Jensen, Ingvild Julie Thue & Gunnæs, Anette Eleonora [Vis alle 10 forfattere av denne artikkelen] (2018). Improving carrier transport in Cu2O thin films by rapid thermal annealing. Journal of Physics: Condensed Matter. ISSN 0953-8984. 30(7). doi: 10.1088/1361-648X/aaa5f4.
• Nordseth, Ørnulf; Kumar, Raj; Bergum, Kristin; Fara, Laurentiu; Foss, Sean Erik & Haug, Halvard [Vis alle 15 forfattere av denne artikkelen] (2017). Optical Analysis of a ZnO/Cu2O Subcell in a Silicon-Based Tandem Heterojunction Solar Cell. Green and Sustainable Chemistry. ISSN 2160-6951. 7(1). doi: 10.4236/gsc.2017.71005.
• Bergum, Kristin; Riise, Heine Nygard; Gorantla, Sandeep Madhukar; Monakhov, Edouard & Svensson, Bengt Gunnar (2016). Thin film Cu2O for solar cell applications. Conference record of the Photovoltaic Specialists Conference. ISSN 0160-8371. 2016-November, s. 2770–2773. doi: 10.1109/PVSC.2016.7750156.
• Lindberg, Per Filip; Riise, Heine Nygard; Bergum, Kristin; Svensson, Bengt Gunnar & Monakhov, Edouard (2016). Electronic properties of Au/Cu2O/n-type Si heterojunction for energy conversion. Conference record of the Photovoltaic Specialists Conference. ISSN 0160-8371. 2016-November, s. 2807–2810. doi: 10.1109/PVSC.2016.7750164.
• Gunnæs, Anette Eleonora; Gorantla, Sandeep Madhukar; Løvvik, Ole Martin; Gan, Jiantuo; Carvalho, Patricia & Svensson, Bengt Gunnar [Vis alle 10 forfattere av denne artikkelen] (2016). Epitaxial strain-induced growth of CuO at Cu2O/ZnO interfaces. Journal of Physical Chemistry C. ISSN 1932-7447. 120(41), s. 23552–23558. doi: 10.1021/acs.jpcc.6b07197. Vis sammendrag

  Cu2O/ZnO has been envisaged as a potential material system for the next generation thin film solar cells. So far, the experimental efforts to obtain conversion efficiencies close to the theoretically predicted value have failed. Combining aberration-corrected (scanning) transmission electron microscopy and density functional theory modelling, we have studied the interfaces between single crystal c-axis oriented ZnO and high-quality magnetron sputtered Cu2O films. Strikingly, our study shows that the first ~5 nm of the Cu-oxide films have the structure of the monoclinic CuO phase. The CuO layer is textured with the (111), (11¯1), (¯111), (1¯1 ¯1), (¯1 ¯11), (1¯11), (¯11¯1) and (100) planes parallel to the (0001) and (000¯1) ZnO interfaces. The ionic arrangement on these planes resembles the hexagonal arrangement of the ZnO interface and epitaxy exists across the interface. A continued epitaxial growth of [111] oriented Cu2O follows resulting in epitaxial 180o rotation twins in the Cu2O layer. For the case with the (100)CuO interfacial plane we have: (111)[1¯10]Cu2O II (100)[011]CuO II (0001)[11¯20]ZnO. Because of a closer lattice matching of CuO with ZnO and Cu2O, the total strain and energy is reduced compared to a pure (111)Cu2O II (0001)ZnO interface. The existence of CuO is anticipated to be a contributing factor for the low conversion efficiencies obtained experimentally.

• Scuderi, V.; Buccheri, Maria Antonietta; Impellizzeri, Giuliana; Di Mauro, A.; Rappazzo, Giancarlo & Bergum, Kristin [Vis alle 8 forfattere av denne artikkelen] (2016). Photocatalytic and antibacterial properties of titanium dioxide flat film. Materials Science in Semiconductor Processing. ISSN 1369-8001. 42, s. 32–35. doi: 10.1016/j.mssp.2015.09.005.
• Bergum, Kristin; Fjellvåg, Helmer & Nilsen, Ola (2015). Thickness dependent structural, optical and electrical properties of Ti-doped ZnO films prepared by atomic layer deposition. Applied Surface Science. ISSN 0169-4332. 332, s. 494–499. doi: 10.1016/j.apsusc.2015.01.124.
• Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Nicotra, Giuseppe & Bergum, Kristin [Vis alle 9 forfattere av denne artikkelen] (2014). TiO2-coated nanostructures for dye photo-degradation in water. Nanoscale Research Letters. ISSN 1931-7573. 9(458). doi: 10.1186/1556-276X-9-458.
• Scuderi, V; Impellizzeri, G; Romano, L; Scuderi, M; Brundo, MV & Bergum, Kristin [Vis alle 14 forfattere av denne artikkelen] (2014). An enhanced photocatalytic response of nanometric TiO<sub>2</sub>wrapping of Au nanoparticles for eco-friendly water applications. Nanoscale. ISSN 2040-3364. 6(19), s. 11189–11195. doi: 10.1039/c4nr02820a.
• Lindberg, Per Filip; Quemener, Vincent; Bergum, Kristin; Gan, Jiantuo; Svensson, Bengt Gunnar & Monakhov, Edouard (2014). Electronic properties of the ZnO:Al/n-Si (100), (110) and (111) interfaces. Materials Research Society Symposium Proceedings. ISSN 0272-9172. 1699 . doi: 10.1557/opl.2014.550.
• Bergum, Kristin; Magraso, Anna; Fjellvåg, Helmer & Nilsen, Ola (2014). Thin film fabrication and characterization of proton conducting lanthanum tungstate. Journal of Materials Chemistry A. ISSN 2050-7488. 2(43), s. 18463–18471. doi: 10.1039/c4ta03359k.
• Bergum, Kristin; Hansen, Per-Anders; Fjellvåg, Helmer & Nilsen, Ola (2014). Structural, electrical and optical characterization of Ti-doped ZnO films grown by atomic layer deposition. Journal of Alloys and Compounds. ISSN 0925-8388. 616, s. 618–624. doi: 10.1016/j.jallcom.2014.07.177.
• Selbach, Sverre Magnus; Løvik, Amund Nordli; Bergum, Kristin; Tolchard, Julian R; Einarsrud, Mari-Ann & Grande, Tor (2012). Crystal structure, chemical expansion and phase stability of HoMnO3 at high temperature. Journal of Solid State Chemistry. ISSN 0022-4596. 196, s. 528–535. doi: 10.1016/j.jssc.2012.07.024.
• Tripathi, S; Petkov, V; Selbach, Sverre Magnus; Bergum, Kristin; Einarsrud, Mari-Ann & Grande, Tor [Vis alle 7 forfattere av denne artikkelen] (2012). Structural coherence and ferroelectric order in nanosized multiferroic YMnO3. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 86(9). doi: 10.1103/PhysRevB.86.094101.
• Bergum, Kristin; Ikeda, Teruyuki & Snyder, Jeffrey G. (2011). Solubility and microstructure in the pseudo-binary PbTe-Ag(2)Te system. Journal of Solid State Chemistry. ISSN 0022-4596. 184(9), s. 2543–2552. doi: 10.1016/j.jssc.2011.07.012.
• Bergum, Kristin; Okamoto, Hiroshi; Fjellvåg, Helmer; Grande, Tor; Einarsrud, Mari-Ann & Selbach, Sverre Magnus (2011). Synthesis, structure and magnetic properties of nanocrystalline YMnO3. Dalton Transactions. ISSN 1477-9226. 40(29), s. 7583–7589. doi: 10.1039/c1dt10536a.

Se alle arbeider i Cristin

• Bergum, Kristin & Haanæs, Øystein Rygg (2023). Hvordan kan solcellene bli mer effektive? [Internett]. Energi og Klima.
• Saxegaard, Kjetil Karlsen; Bergum, Kristin; Vines, Lasse & Monakhov, Eduard (2023). The effect of annealing on opto-electronic properties of ZnON films.
• Monakhov, Eduard; Bergum, Kristin; Vines, Lasse & Saxegaard, Kjetil Karlsen (2023). The UiO semiconductor group: Towards tandems with ZnON.
• Saxegaard, Kjetil Karlsen; Monakhov, Eduard; Vines, Lasse & Bergum, Kristin (2023). The effect of annealing on ZnON intended for solar cell applications.
• Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnOxNy films .
• Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on ZnON films.
• Karlsen, Kjetil; Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnOxNy films.
• Karlsen, Kjetil; Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnON films.
• Karlsen, Kjetil; Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnON films.
• Karlsen, Kjetil; Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). Electronic properties and dominant levels in ZnON.
• Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnON films.
• Saxegaard, Kjetil Karlsen; Bergum, Kristin; Monakhov, Eduard & Vines, Lasse (2022). The effect of oxygen and nitrogen concentrations on Opto-electronic properties of ZnON films.
• Bergum, Kristin (2022). Solceller: I dag og i morgen.
• Bergum, Kristin (2022). Designing tandem solar cells.
• Bergum, Kristin (2022). A comparison of thin film deposition techniques.
• Bergum, Kristin (2022). Designing tandem solar cells.
• Bergum, Kristin; Selj, Josefine Helene Krogh & Melteig, Elina (2022). Glemmer Norge sola når vi snakker om fornybar energi? [Internett]. Universitetsplassen podcast for UiO, ep 85.
• Karlsen, Kjetil; Monakhov, Eduard; Vines, Lasse & Bergum, Kristin (2021). Electronic properties and the dominant levels in ZnON.
• Bergum, Kristin; Vines, Lasse & Monakhov, Eduard (2021). Electronic properties and the dominant levels in ZnON.
• Bergum, Kristin & Vogt, Yngve (2021). Kan hente ut 50 prosent mer strøm fra solceller. [Tidsskrift]. Apollon.
• Bergum, Kristin & Aarmo, Johannes (2021). Solceller. [Radio]. Radio Trøndelag.
• Karlsen, Kjetil; Monakhov, Eduard; Bergum, Kristin; Vines, Lasse & Thue Jensen, Ingvild (2021). Electronic properties and dominant levels in ZnON.
• Bergum, Kristin (2020). Designing materials for tandem solar cells.
• Bergum, Kristin (2020). Tandem solar cells with novel materials.
• Karlsen, Kjetil; Bergum, Kristin & Monakhov, Eduard (2020). ZnOxNy as a top cell absorber candidate in tandem solar cells.
• Torgersen, Eivind & Bergum, Kristin (2020). Doble solceller kan øke effektiviteten med 50 prosent. Titan.uio.no.
• Bergum, Kristin (2019). Silicon-based tandem solar cells.
• Bergum, Kristin (2019). Thin film deposition techniques.
• Nyborg, Martin; Bergum, Kristin; Monakhov, Eduard & Svensson, Bengt Gunnar (2018). Nitrogen Doping of Sputtered Cuprous Oxide Thin Films by ion Implantation .
• Nyborg, Martin; Monakhov, Eduard & Bergum, Kristin (2018). Lithium Doped DC Magnetron Sputtered Cu2O Thin Films .
• Nordseth, Ørnulf; Fara, Laurentiu; Kumar, Raj; Foss, S. E.; Dumitru, C. & Muscurel, V.-F. [Vis alle 17 forfattere av denne artikkelen] (2017). Electro-Optical Modeling of a ZnO/Cu2O Subcell in a Silicon-Based Tandem Heterojunction Solar Cell.
• Nordseth, Ørnulf; Kumar, Raj; Bergum, Kristin; Fara, Laurentiu; Chilibon, I.la & Foss, S. E. [Vis alle 8 forfattere av denne artikkelen] (2017). Silicon-Based Tandem Solar Cells Boosting the Performance Using Non-Toxic Metal Oxides. GIT Laboratory Journal Europe. ISSN 1611-6038.
• Kumar, Raj; Bergum, Kristin; Riise, Heine Nygard; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Impact of post annealing on hydrogen implanted Cu2O thin film for solar cell applications.
• Kumar, Raj; Bergum, Kristin; Riise, Heine Nygard; Azarov, Alexander; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Impact of post deposition annealing on electrical properties of Cu2O thin films.
• Kumar, Raj; Bergum, Kristin; Riise, Heine Nygard; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Electrical and optical characterization of p type Cu2O thin film for solar cell applications.
• Bergum, Kristin; Borgersen, Jon Arthur; Ellingsen, Josef Gert Åsheim; Frodason, Ymir Kalmann; Galeckas, Augustinas & Ingebrigtsen, Mads Eide [Vis alle 8 forfattere av denne artikkelen] (2017). Omvisning MiNaLab.
• Bergum, Kristin; Borgersen, Jon Arthur; Ellingsen, Josef Gert Åsheim; Hallén, Anders; Ingebrigtsen, Mads Eide & Kuznetsov, Andrej (2017). Omvisning MiNaLab, Slemdal skole 4. trinn.
• Bergum, Kristin (2017). Physical vapour deposition (PVD).
• Frodason, Ymir Kalmann; Bergum, Kristin; Sky, Thomas Neset; Ingebrigtsen, Mads Eide; Borgersen, Jon & Ellingsen, Josef Gert Åsheim [Vis alle 8 forfattere av denne artikkelen] (2017). MiNa-Lab tour highlighting LENS activities.
• Monakhov, Edouard; Bathen, Marianne Etzelmüller; Bergum, Kristin; Sky, Thomas Neset & Weiser, Philip Michael (2017). Omvisning for the National Natural Science Foundation of China.
• Bathen, Marianne Etzelmüller; Bergum, Kristin; Ellingsen, Josef Gert Åsheim; Grini, Sigbjørn; Sky, Thomas Neset & Aarseth, Bjørn Brevig (2017). Omvisning for Arendal VGS.
• Johansen, Klaus Magnus H; Bergum, Kristin; Riise, Heine Nygard & Grini, Sigbjørn (2017). Advanced characterization of solar energy materials and novel solar cell concepts.
• Bergum, Kristin; Nilsen, Ola & Fjellvåg, Helmer (2014). Structural, electrical and optical characterization of Ti-doped ZnO films grown by atomic layer deposition. Journal of Alloys and Compounds. ISSN 0925-8388. doi: 10.1016/j.jallcom.2014.07.177.
• Lindberg, Per Filip; Bergum, Kristin; Svensson, Bengt Gunnar & Monakhov, Edouard (2014). Electronic Properties of the ZnO/Si(100), (110) and (111) Interface.
• Lindberg, Per Filip; Quemener, Vincent; Bergum, Kristin; Gan, Jiantuo; Svensson, Bengt Gunnar & Monakhov, Edouard (2014). Electronic properties of the ZnO:Al/n-Si (100), (110) and (111) interfaces.
• Selbach, Sverre Magnus; Løvik, Amund Nordli; Bergum, Kristin; Tolchard, Julian R; Einarsrud, Mari-Ann & Grande, Tor (2012). Oxygen non-stoichiometry in hexagonal manganites.
• Selbach, Sverre Magnus; Løvik, Amund Nordli; Bergum, Kristin; Tolchard, Julian R; Einarsrud, Mari-Ann & Grande, Tor (2012). Crystal structure, phase transition, chemical expansion and defect chemistry of hexagonal HoMnO3.
• Selbach, Sverre Magnus; Løvik, Amund Nordli; Bergum, Kristin; Tolchard, Julian R; Einarsrud, Mari-Ann & Grande, Tor (2012). HoMnO3+/-d - stability, structure and stoichiometry.
• Selbach, Sverre Magnus; Tybell, Thomas; Einarsrud, Mari-Ann; Grande, Tor & Bergum, Kristin (2011). Multiferroism in BiFeO3 and YMnO3 nanoparticles.
• Both, Kevin Gregor; Chatzitakis, Athanasios; Bergum, Kristin; Hansen, Per-Anders Stensby; Prytz, Øystein & Norby, Truls (2023). Plasmonically Enhanced Photocatalysis: Synthesis, Physical Properties, and Applications. University of Oslo Livrary. ISSN 1501-7710. Fulltekst i vitenarkiv Vis sammendrag

  In this work, plasmonic metal nanoparticles (MNPs) are utilized to improve the photoelectrochemical (PEC) response of strontium titanate (STO). These MNPs were introduced by either direct exsolution, i.e., nickel (Ni), copper (Cu), iron (Fe), ruthenium (Ru), and silver (Ag), or by galvanically replacing exsolved less noble MNPs, i.e., Ni by Gold (Au), or Cu for Ag. Au, Ag, and Cu were the materials chosen with significant plasmonic activity; Fe, Ru, Pt, and Ni were used to make MNPs with minimal plasmonic response. Two different stoichiometries of STO were synthesized. One, La-doped A-site deficient STO (La0.6Sr0.2Ti0.9Ni0.1O3–x), was exclusively doped with Ni and utilized as powder samples. The other stoichiometry was A-site excess STO (Sr1.07Ti0.93M0.07O3±δ, where M is the dopant) was doped with various metals. These excess perovskites were studied in thin film and powder forms. A-site excess STO thin films were deposited by pulsed laser deposition on silicon substrates. The as-deposited thin films appeared nanocrystalline or amorphous until the exsolution process was engaged. The exsolution step was studied explicitly for these A-site excess STO thin films where the formation of MNPs occurred not only at or near the thin film surface but also on grain interfaces and in bulk. Moreover, the dopant diffused significantly during the process. While the size of the template particles depended on the exsolution conditions, the galvanic replacement reaction determined the shapes and sizes of the newly formed MNPs. The replacement time and the form (thin film/powder) of STO influenced the results, both completely replaced particles and partially replaced particles with complex structures were obtained. Additionally, more prolonged galvanic replacement reactions lead to larger particles. In turn, the specific shape of the plasmonic MNPs determined the localized surface plasmon resonance band shape and peak position. Overall, exsolution leads to well-socketed MNPs, a property seemingly inherited by the MNPs created by galvanic replacement. Well-socketed MNPs are extremely difficult to obtain by any other technique and have a favorable localized surface plasmon resonance peak shift. The PEC response revealed that reducing STO first decreases the material’s response. Reducing it further, however, increases the PEC response significantly. Au MNPs increase the PEC performance until the MNPs reach a specific size and subsequently decrease the PEC performance when growing more prominent. This work highlights the ease by which well-socketed plasmonic MNPs can be created, some impossible to synthesize by another technique, and how different reaction conditions can change the shape and size of the MNPs, ultimately tuning the localized surface plasmon resonance band shape and peak position. The method of exsolution and galvanic replacement reaction was generalized by utilizing different elements, implying that the tuning of catalytic activity depends on the choice of elements and reaction conditions.

• Vikne, Martin Schønning; Prytz, Øystein; Nguyen, Phuong Dan & Bergum, Kristin (2022). TEM Characterization of ZnOxNy for Tandem Solar Cell Applications. Universitetet i Oslo.
• Bergsbak, Ingvild; Bergum, Kristin; Nordseth, Ørnulf & Karlsen, Kjetil (2021). Numerical device simulations of ZnOxNy for Si-based tandem solar cells using Silvaco Atlas. Universitetet i Oslo.
• Zariouh, Osama; Monakhov, Eduard & Bergum, Kristin (2020). Deposition of phase-pure Cu2O by magnetron sputtering. Universitetet i Oslo.
• Sødahl, Elin Dypvik; Bergum, Kristin & Vines, Lasse (2020). HiPIMS deposition and characterization of amorphous ZnOxNy for solar cell applications. Universitetet i Oslo.
• Bergum, Kristin; Nilsen, Ola & Fjellvåg, Helmer (2014). Energy materials by atomic Layer Deposition. Universitetet i Oslo.

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