Vegard Skiftestad Olsen

• Kjeldby, Snorre Braathen; Nielsen, Dina Marie; Cooil, Simon Phillip; Frodason, Ymir Kalmann; Zacharaki, Eirini & Lee, In Hwan [Show all 10 contributors for this article] (2025). Tuning Properties of II-IV-Nitrides for Optoelectronic Applications. Advanced Optical Materials. 13(36). doi: 10.1002/adom.202502634. Full text in Research Archive Show summary

  The earth-abundant II-IV-nitrides ZnSnN2 and ZnGeN2 are direct bandgap semiconductors with a wurtzite-derived crystal structure. Their alloys, ZnSnxGe1 − xN2, have bandgaps tunable across the full visible spectrum, making them interesting for many optoelectronic applications. Here, electrical, structural, and optical properties of near-stoichiometric ZnSnxGe1 − xN2 alloys, i.e., where [Zn]/([Zn]+[Ge]+[Sn]) ≈ 0.5, are reported, for samples synthesized by reactive magnetron sputtering. These results reveal unprecedentedly high electrical mobilities in Ge-rich alloys, with values of 136 and 400 cm2/Vs at room-temperature and ≈100 K, respectively. The bandgaps are determined from optical absorption measurements combined with hybrid density functional calculations and reveal a significant Burstein–Moss shift in the Sn rich alloys. Finally, band alignments are determined in the sputter-grown thin films by combining optical transmission measurements, hybrid density functional calculations, and UV photoelectron spectroscopy measurements, where the bandgap variation is predominantly caused by a shift of the conduction band edge. This work elucidates in unprecedented detail the tuning of optical and electrical properties in ZnSnxGe1 − xN2 by variation of the chemical composition, where bandgap values of alloys with x ∈ [0.5−0.7] are suitable for top cell absorbers in two-terminal tandem solar cells assuming a Si bottom cell.

• Bergsbak, Ingvild; Nordseth, Ørnulf; Saxegaard, Kjetil Karlsen; Olsen, Vegard Skiftestad; Wenckstern, Holger Von & Bergum, Kristin (2024). Device Simulation of 25.9% Efficient ZnOxNy/Si Tandem Solar Cell. Advanced Theory and Simulations. 7(12). doi: 10.1002/adts.202400252. Full text in Research Archive Show summary

  The novel, high electron mobility material ZnOxNy has been investigated theoretically as an absorber in a two-terminal tandem solar cell. In addition to its high mobility, ZnOxNy can attain sufficiently low carrier concentration to enable pn-junctions, and has a tunable bandgap around the 1.7 eV range. It is therefore suitable for pairing with a Si-based bottom cell. In addition to the ZnOxNy layer, the tandem cell consists of a Cu2O emitter and a Si heterojunction bottom cell. A buffer layer is introduced between the emitter and absorber in the top cell to mediate a large valence band offset that resulted in a poor fill factor, FF. A ZnOxNy buffer layer bandgap of 1.5 eV gave the highest power conversion efficiency (PCE). The objective is to estimate the optimal performance of ZnOxNy in a tandem solar cell. The dependence of current–voltage (J–V) characteristics on thickness, mobility and carrier concentration in the ZnOxNy layer is evaluated, and found to yield maximum performance with 0.35 𝛍m, 250 cm2 Vs–1 and 1016 cm−3, respectively. Using these conditions, the J–V parameters of the device under AM1.5 illumination are short circuit current density, JSC = 17.76 mA cm−2, open circuit voltage, VOC = 1.74 V, FF = 83.8% and PCE = 25.9%. With this, it is reported on, to the best of the knowledge, the first device simulation based on ZnOxNy.

• Frodason, Ymir Kalmann; Galeckas, Augustinas; Olsen, Vegard Skiftestad; Weiser, Philip Michael; Galazka, Zbigniew & Walle, Chris G. Van De [Show all 7 contributors for this article] (2024). Intrinsic origins of broad luminescence in melt-grown ZnGa2 O4 single crystals. PHYSICAL REVIEW MATERIALS. 8(9). doi: 10.1103/PhysRevMaterials.8.094604. Full text in Research Archive
• Olsen, Vegard Skiftestad; Frodason, Ymir Kalmann; Hommedal, Ylva Knausgård; Nielsen, Dina Marie; Weiser, Philip Michael & Johansen, Klaus Magnus H [Show all 9 contributors for this article] (2022). Li and group-III impurity doping in ZnSnN2: Potential and limitations. PHYSICAL REVIEW MATERIALS. 6(12), p. 1–8. doi: 10.1103/PhysRevMaterials.6.124602. Full text in Research Archive Show summary

  II–IV nitrides and their alloys represent an earth-abundant and potentially cost-efficient alternative to the well-developed AlN-GaN-InN system. A major drawback with the II–IV nitrides is that ZnSnN2, the lowest band gap material, exhibits unfavorably high carrier concentrations for as-grown, stoichiometric material, limiting the material systems potential use in applications such as solar cells and light-emitting diodes. Lithium (Li) has been suggested as a shallow acceptor defect in ZnSnN2 if substituting for Zn, and hence doping with Li has been identified as a possible way to improve the electronic properties. Herein, theoretical calculations by hybrid functional density functional theory have been employed and extended to include defect complexes as well, which to this point remained unexplored. The calculations reveal that even though Li on the Zn site (the LiZn) is an acceptor, the defect may easily complex with the Lii donor, rendering the complex neutral. Our theoretical findings are supported by a Li-doping series of ZnSnN2, where a doping concentration ranging from 2.10×1019cm−3 to 1.85×1020cm−3 was obtained. The n-type carrier concentration was found to be unaffected by the doping concentration, and no systematic change in the absorption onset, probably affected by a Burstein-Moss shift, was observed. Possible group-III dopants, as have been found to yield interesting results for ZnGeN2, such as In, Ga, Al, and B, have also been investigated as an alternative dopant in ZnSnN2.

• Olsen, Vegard Skiftestad; Øversjøen, Vetle; Gogova-Petrova, Daniela; Pecz, Bela; Galeckas, Augustinas & Borgersen, Jon Arthur [Show all 9 contributors for this article] (2021). ZnSnN2 in Real Space and k-Space: Lattice Constants, Dislocation Density, and Optical Band Gap. Advanced Optical Materials. doi: 10.1002/adom.202100015. Full text in Research Archive
• Gogova-Petrova, Daniela; Olsen, Vegard Skiftestad; Bazioti, Kalliopi; Lee, In-Hwan; Prytz, Øystein & Vines, Lasse [Show all 7 contributors for this article] (2020). High electron mobility single-crystalline ZnSnN2 on ZnO (0001) substrates. CrysteEngComm. 22(38), p. 6268–6274. doi: 10.1039/d0ce00861c. Full text in Research Archive Show summary

  Making a systematic effort, we have developed single-crystalline ZnSnN2 on ZnO (0001) by reactive magnetron co-sputtering. Epitaxial growth was achieved at 350 °C by co-sputtering from metal targets in a nitrogen atmosphere, and confirmed by transmission electron microscopy (TEM) measurements. TEM verified that the layers are single-crystalline of hexagonal phase, exhibiting an epitaxial relationship with the substrate described by: [11−20]ZnSnN2//[11−20]ZnO and [0001]ZnSnN2//[0001]ZnO. The screw-type threading dislocations originating from the ZnSnN2/ZnO interface were identified as the dominant extended defects. More specifically, we report a pioneering measurement of the dislocation density in this material of 1.5 × 1011 cm−2. Even though there are no literature data for direct comparison, such values are typical of heteroepitaxial growth of III-nitride layers without applying defect density reduction strategies. The films demonstrated a high electron mobility of 39 cm2 V−1 s−1 and 63 cm2 V−1 s−1 for stoichiometric and Zn-rich layers, respectively, while the electron carrier density remained in the low 1019 cm−3 range as determined by the Hall effect measurements at room temperature. Optical bandgaps of 1.86 eV and 1.72 eV were determined for the stoichiometric and Zn-rich samples, respectively. As such, we conclude that ZnSnN2 is an earth-abundant, environmentally-friendly semiconductor and is a promising candidate for cost efficient components in optoelectronics and photovoltaics.

• Karsthof, Robert Michael; Wenckstern, Holger von; Olsen, Vegard Skiftestad & Grundmann, Marius (2020). Identification of LiNi and VNi acceptor levels in doped nickel oxide. APL Materials. 8(12). doi: 10.1063/5.0032102. Full text in Research Archive Show summary

  Nickel oxide, in particular in its doped, semiconducting form, is an important component of several optoelectronic devices. Doped NiO is commonly achieved either by incorporation of lithium, which readily occupies Ni sites substitutionally, producing the LiNi acceptor, or by supplying reactive oxygen species during NiO film deposition, which leads to the formation of Ni vacancies (VNi). However, the energetic position of these acceptors in the NiO bandgap has not been experimentally determined until today. In this work, we close this knowledge gap by studying rectifying n++p heterojunctions consisting of NiO thin films grown on top of fluorine-doped tin oxide. These structures show sufficient rectification to perform electric characterization by defect spectroscopic techniques, specifically capacitance–voltage and thermal admittance spectroscopy. Using these methods, the (0/−) charge transition levels are determined to be 190 meV and 409 meV above the valence band edge for the LiNi and the VNi acceptor, respectively.

• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Kuznetsov, Andrej; Vines, Lasse & Prytz, Øystein (2020). Formation of N2 bubbles along grain boundaries in (ZnO)1−x(GaN)x: nanoscale STEM-EELS studies. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 22(7), p. 3779–3783. doi: 10.1039/c9cp06025a. Full text in Research Archive Show summary

  Direct evidence of N2 formation after annealing of (ZnO)1−x(GaN)x alloys was revealed. N2 was trapped by VZn+Ga-clusters, forming faceted voids along grain boundaries. This study shows that N–N bonding is a competitive path for nitrogen after annealing, in addition to the increasing Ga–N bonds, indicating that N in O substitution sites (NO) is not a stable configuration.

• Olsen, Vegard Skiftestad; Bazioti, Kalliopi; Baldissera, Gustavo; Azarov, Alexander; Prytz, Øystein & Persson, Clas [Show all 9 contributors for this article] (2019). Effects of Substrate and Post-Deposition Annealing on Structural and Optical Properties of (ZnO)1-x(GaN)x Films. Physica status solidi (b). ISSN 0370-1972. 256(6). doi: 10.1002/pssb.201800529. Full text in Research Archive Show summary

  The structural and optical properties of magnetron sputtered thin films of (ZnO)1−x(GaN)x deposited on zinc oxide, sapphire, and silicon oxide are studied as a function of strain accumulation and post‐deposition anneals at 600–800 °C. For the experimental conditions studied, we found that different amounts of tensile strain accumulated in the samples practically does not affect the strong bandbowing effect, that is, optical bandgap, observed in the as‐deposited alloys. In its turn, post‐deposition annealing results in a reduction of the tensile strain and dislocation density in the films, as measured by both X‐ray diffraction and transmission electron microscopy, corroborating an increase in the crystal quality. In addition, the grain size is found to increase with annealing temperature, for example, mean values of 20 nm up to 50 nm were measured for the alloys with x = 0.15. Meanwhile, the full‐width at half maximum of the (0002) X‐ray diffraction reflection increases with annealing temperature, but with only a small increase in bandgap energies for the x = 0.15 sample. However, this observation was explained combining the experimental data and first‐principles calculations based on density functional theory, showing that the increase in the amount of Ga‐N bonds lowers the total energy of the system. As such, we conclude that the thermal treatments increase the Ga‐N ordering, resulting in several contributions or a widening of the diffraction peaks.

• Olsen, Vegard Skiftestad; Baldissera, Gustavo; Zimmermann, Christian; Granerød, Cecilie Skjold; Bazioti, Kalliopi & Galeckas, Augustinas [Show all 11 contributors for this article] (2019). Evidence of defect band mechanism responsible for band gap evolution in (ZnO)1−x(GaN)x alloys. Physical review B (PRB). ISSN 2469-9950. 100(16). doi: 10.1103/PhysRevB.100.165201. Full text in Research Archive Show summary

  It is known that (ZnO)1−x(GaN)x alloys demonstrate remarkable energy band bowing, making the material absorb in the visible range, in spite of the binary components being classical wide band gap semiconductors. However, the origin of this bowing is not settled; two major mechanisms are under debate: Influence of the orbital repulsion and/or formation of a defect band. In the present work, we applied a combination of the absorption and emission measurements on the samples exhibiting an outstanding nanoscale level of (ZnO)1−x(GaN)x homogeneity as monitored by the high resolution electron microscopy equipped with the energy dispersive x-ray analysis and the electron energy loss spectroscopy; moreover the experimental data were set in the context of the computational analysis of the alloys employing density functional theory and quasiparticle GW approximation. A prominent discrepancy in the band gap values as deduced from the absorption and emission experiments was observed systematically for the alloys with different compositions and interpreted as evidence for the absorption gap shrinking due to the defect band formation. Computational data support the argument, revealing only minor variations in the bulk of the conduction and valence band structures of the alloys, except for a characteristic “tail” in the vicinity of the valence band maximum. As such, we conclude that the energy gap bowing in (ZnO)1−x(GaN)x alloys is due to the defect band formation, presumably at the top of the valence band maximum.

• Olsen, Vegard Skiftestad; Bazioti, Kalliopi; Azarov, Alexander; Svensson, Bengt Gunnar; Kuznetsov, Andrej & Prytz, Øystein [Show all 7 contributors for this article] (2018). Bandgap bowing in crystalline (ZnO)1-x(GaN)x thin films; influence of composition and structural properties. Semiconductor Science and Technology. ISSN 0268-1242. 34, p. 1–7. doi: 10.1088/1361-6641/aaee4a. Full text in Research Archive
• Riise, Heine Nygard; Olsen, Vegard Skiftestad; Azarov, Alexander; Galeckas, Augustinas; Sky, Thomas Neset & Svensson, Bengt Gunnar [Show all 7 contributors for this article] (2016). Local homoepitaxy of zinc oxide thin films by magnetron sputtering. Thin Solid Films. ISSN 0040-6090. 601, p. 18–21. doi: 10.1016/j.tsf.2015.09.043. Full text in Research Archive

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• Frøland, Mariann Carlsen; Furlan, Riccardo; Bygdås, Martin; Olsen, Vegard Standeren; Bathen, Marianne Etzelmüller & Vines, Lasse (2026). Sputtered Aluminum Nitride Thin Films as Waveguides and Hosts for Single-Photon Emitters. Full text in Research Archive Show summary

  AlN is a promising material for hosting quantum emitters and for use as optical waveguides. This work investigates the emission and structural properties of sputtered aluminium nitride thin films, with the aim of integrating these films into a quantum sensor.

• Olsen, Vegard Standeren (2025). CC-NorChip – What’s in it for us? Full text in Research Archive
• Persson, Aksel Faanes; Gjørv, Alexandra Bech; Bernstein, Ralph William; Olsen, Vegard Standeren; Hoofman, Romano & Bathen, Marianne Etzelmüller (2025). Kampen om fremtiden: Mikrobrikker og kvanteteknologi (live-opptak fra teknologifestivalen Kongsberg Agenda 2025). doi: https:/shows.acast.com/smart-forklart/episodes/kampen-om-fremtiden-mikrobrikker-og-kvanteteknologi-live. Full text in Research Archive
• Olsen, Vegard Skiftestad (2025). Pressemelding: CC-NorChip offisielt åpnet av digitaliseringsministeren. [Internet]. NTB Kommunikasjon. doi: https:/kommunikasjon.ntb.no/pressemelding/18720033/cc-norchip-offisielt-apnet-av-digitaliseringsministeren?publisherId=7235542&lang=no. Full text in Research Archive Show summary

  Det nye nasjonale senteret skal bidra til økt kompetanse, og bistå norsk næringsliv med å ta i bruk halvleder- og sensorteknologi i samarbeid med Europa.

• Olsen, Vegard Skiftestad & Skomsvoll, Yngve (2025). Framtidas læring. Næringslivet betaler - vil bare ha et ja fra kommunen. [Journal]. Gjengangeren. Full text in Research Archive
• Olsen, Vegard Skiftestad & Nordeide, Thomas Vie (2025). Digitaliseringsministeren ble imponert. [Internet]. Univ. i Sør-Øst Norge. doi: https:/www.usn.no/nyhetsarkiv/digitaliseringsministeren-ble-imponert. Full text in Research Archive Show summary

  Karianne Tung, som hadde satt av fire timer til besøket ved USN, fikk innsikt i hvordan mikroelektronikk, kunstig intelligens og autonome systemer utvikles i tett samarbeid med næringslivet.

• Kjeldby, Snorre Braathen; Olsen, Vegard Skiftestad; Frodason, Ymir Kalmann; Zacharaki, Eirini; Cooil, Simon Phillip & Vines, Lasse [Show all 12 contributors for this article] (2025). Thin film top cell absorbers for multijunction solar cells. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Olsen, Vegard Skiftestad & Vines, Lasse (2024). Hvor går veien? Kvanteteknologiens potensiale i fremtidens teknologi​. Full text in Research Archive
• Olsen, Vegard Skiftestad; Karlsen, Kjetil; Langørgen, Amanda; Andreassen, Magnus & Hommedal, Ylva Knausgård (2021). Omvisning UiO MiNaLab for FA bachelorstudenter. Full text in Research Archive
• Olsen, Vegard Skiftestad; Kjeldby, Snorre Braathen; Karlsen, Kjetil & Hommedal, Ylva Knausgård (2021). Omvisning UiO MiNaLab for MENA bachelorstudenter. Full text in Research Archive
• Olsen, Vegard Skiftestad (2021). Omvisning UiO MiNaLab for MENA masterstudenter. Full text in Research Archive
• Olsen, Vegard Skiftestad; Hommedal, Ylva Knausgård; Kjeldby, Snorre Braathen & Karlsen, Kjetil (2021). Omvisning UiO MiNaLab for Tekna representanter. Full text in Research Archive
• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Azarov, Alexander; Johansen, Klaus Magnus H; Kuznetsov, Andrej & Vines, Lasse [Show all 7 contributors for this article] (2021). Thermal evolution of point and extended defects in N-implanted ZnO and (ZnO)1−x(GaN)x thin films: STEM-EELS investigations. Full text in Research Archive
• Olsen, Vegard Skiftestad; Øversjøen, Vetle; Frodason, Ymir Kalmann; Cooil, Simon; Lee, In-Hwan & Vines, Lasse [Show all 7 contributors for this article] (2021). Electrical control in ZnSnN2 by tailoring intrinsic and extrinsic defects. Full text in Research Archive
• Karsthof, Robert Michael; Wenckstern, Holger von; Olsen, Vegard Skiftestad & Grundmann, Marius (2021). Identification of LiNi and VNi acceptor levels in doped nickel oxide. Full text in Research Archive
• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Azarov, Alexander; Johansen, Klaus Magnus H; Svensson, Bengt Gunnar & Kuznetsov, Andrej [Show all 8 contributors for this article] (2020). Role of nitrogren in defect evolution in ZnO and (ZnO)₁−ₓ(GaN)ₓ: STEM-EELS nanoscale investigations. Full text in Research Archive
• Bathen, Marianne Etzelmüller & Olsen, Vegard Skiftestad (2020). Foredrag for MENA-studenter om halvlederfysikk. Full text in Research Archive
• Bathen, Marianne Etzelmüller & Olsen, Vegard Skiftestad (2020). Foredrag for FA-studenter om halvlederfysikk. Full text in Research Archive
• Bathen, Marianne Etzelmüller & Olsen, Vegard Skiftestad (2019). Omvisning for FA og ELITE. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Borgersen, Jon Arthur; Karlsen, Kjetil; Nyborg, Martin; Olsen, Vegard Skiftestad & Reinertsen, Vilde Mari [Show all 7 contributors for this article] (2019). Skolebesøk ved MiNaLab. Full text in Research Archive
• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Azarov, Alexander; Kuznetsov, Andrej; Vines, Lasse & Prytz, Øystein (2019). Defect formation and thermal evolution in ZnO-based structures (Highlight talk). Full text in Research Archive
• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Alexander, Azarov; Kuznetsov, Andrej; Vines, Lasse & Prytz, Øystein (2019). STEM-EELS investigation of defect formation and thermal evolution in ZnO. Full text in Research Archive
• Bazioti, Kalliopi; Olsen, Vegard Skiftestad; Johansen, Klaus Magnus H; Azarov, Alexander; Kuznetsov, Andrej & Vines, Lasse [Show all 7 contributors for this article] (2019). Transmission Electron Microscopy methods for atomic-scale investigations of semiconductor properties. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Ingebrigtsen, Mads Eide; Olsen, Vegard Skiftestad; Rønning, Vegard & Vines, Lasse (2018). Omvisning for studieprogrammene FA og ELITE. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2018). (ZnO)1-X(GaN)X thin films studied by high-resolution structural and spectroscopic imaging. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2018). Structural-chemical characterization and bandgap measurements at the nanoscale of (ZnO)1-X(GaN)X thin films using (S)TEM methods. Full text in Research Archive
• Olsen, Vegard Skiftestad; Bazioti, Kalliopi; Azarov, Alexander; Granerød, Cecilie Skjold; Svensson, Bengt Gunnar & Kuznetsov, Andrej [Show all 8 contributors for this article] (2018). Bandgap bowing in crystalline (ZnO)1-x(GaN)x thin films. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Borgersen, Jon Arthur; Grini, Sigbjørn; Johansen, Klaus Magnus H; Nyborg, Martin & Olsen, Vegard Skiftestad [Show all 7 contributors for this article] (2017). Omvisning FAM. Full text in Research Archive
• Riise, Heine Nygard; Bathen, Marianne Etzelmüller; Grini, Sigbjørn; Olsen, Vegard Skiftestad & Sky, Thomas Neset (2017). Omvisning MENA. Full text in Research Archive
• Riise, Heine Nygard; Aarseth, Bjørn Brevig; Kjeldstad, Torunn; Borgersen, Jon Arthur & Olsen, Vegard Skiftestad (2017). Besøk frå deltakarar i Fysikk-OL. Full text in Research Archive
• Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Kuznetsov, Andrej (2017). Bandgap reduction and the effects of post-deposition annealing on (ZnO)1-X(GaN)X thin films. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2017). Structural characterization and nanoscale bandgap measurements of (ZnO)1-X(GaN)X thin films. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2017). Structural/chemical characterization and bandgap measurements of (ZnO)1-X(GaN)X thin films using (S)TEM methods. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2017). (S)TEM characterization of magnetron sputtered ZnO:GaN alloy thin films. Full text in Research Archive
• Bazioti, Kalliopi; Granerød, Cecilie Skjold; Olsen, Vegard Skiftestad; Vines, Lasse; Svensson, Bengt Gunnar & Prytz, Øystein (2017). Structural and chemical characterization of (ZnO)1-X(GaN)X thin films using (S)TEM methods. Full text in Research Archive
• Aasen, Jan Harald; Bergum, Kristin; Olsen, Vegard Skiftestad & Saxegaard, Kjetil Karlsen (2024). Developing ZnON for tandem solar cells. Universitetet i Oslo. Full text in Research Archive
• Nielsen, Dina Marie & Olsen, Vegard Skiftestad (2023). Tailoring functional properties of earth-abundant II-IV-nitride alloys: towards tandem solar cell applications. Universitetet i Oslo. Full text in Research Archive
• Vigneswaran, Nirun; Vines, Lasse & Olsen, Vegard Skiftestad (2022). Deponering og karakterisering av polykrystallinsk SnO for solcelle applikasjoner. Universitetet i Oslo. Full text in Research Archive
• Øversjøen, Vetle; Vines, Lasse & Olsen, Vegard Skiftestad (2021). Development of Earth Abundant ZnSnN2 for Solar Cell Applications. Universitetet i Oslo. Full text in Research Archive
• Olsen, Vegard Skiftestad (2020). Functional Properties and Band Gap Engineering of ZnO-GaN Alloys. Universitetet i Oslo. Full text in Research Archive Show summary

  Renewable energy sources play a vital role in handling the increasing energy demand, as well as the aim to reduce carbon emissions. New materials for solar cell applications are being developed for this sole reason. The ZnO-GaN (ZOGN) semiconductor alloys, consisting of two industrial well-proven materials with intriguing optical properties, have been found to yield tunable absorption from UV- and well in to the visible part of the solar spectrum, due to the so-called band bowing effect. The alloys have been developed and utilized for hydrogen production through overall water-splitting, and also show promising properties for optoelectronics. In this work, the fundamental properties of ZOGN alloys have been investigated with the aim of utilization in applications as solar cells, photo detectors and photo diodes. Highly crystalline alloy thin films, grown using magnetron sputtering, have been investigated in terms of structural, optical and electrical properties. In particular, the mechanisms governing the band bowing effect observed in the materials have been explored, in order to understand and control the tunable absorption. This control is highly relevant for applications as solar cells, photo diodes and overall water-splitting.

• Olsen, Vegard Skiftestad (2020). Functional Properties and Bang Gap Engineering of ZnO-GaN Alloys. Det matematisk-naturvitenskapelige fakultet. Full text in Research Archive

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