Research Centre for Sustainable Solar Cell Technology (SuSolTech)

• Vukovic, Marija; Wiig, Marie Syre; Benatto, Gisele Alves dos Reis; Olsen, Espen & Burud, Ingunn (2024). A review of imaging methods for detection of photoluminescence in field-installed photovoltaic modules. Progress in Energy. ISSN 2516-1083. 6(3). doi: 10.1088/2516-1083/ad4250.
• Hammann, Benjamin; Aßmann, Nicole; Schön, Jonas; Kwapil, Wolfram; Schindler, Florian & Roder, Sebastian [Show all 8 contributors for this article] (2023). Understanding the impact of the cooling ramp of the fast-firing process on light- and elevated-temperature-induced degradation. Solar Energy Materials and Solar Cells. ISSN 0927-0248. 259, p. 1–9. doi: 10.1016/j.solmat.2023.112462.
• Søndenå, Rune; Weiser, Philip Michael; Mosel, Frank; Aßmann, Nicole; Hansen, Per-Anders Stensby & Monakhov, Eduard (2023). Controlling the hydrogen concentration in boron- and gallium-doped silicon wafers. AIP Conference Proceedings. ISSN 0094-243X. 2826(1), p. 110008-1–110008-6. doi: 10.1063/5.0141155. Full text in Research Archive
• Hammann, Benjamin; Assmann, Nicole; Weiser, Philip Michael; Kwapil, Wolfram; Niewelt, Tim & Schindler, Florian [Show all 9 contributors for this article] (2023). The Impact of Different Hydrogen Configurations on Light- and Elevated-Temperature- Induced Degradation. IEEE Journal of Photovoltaics. ISSN 2156-3381. 13(2), p. 224–235. doi: 10.1109/JPHOTOV.2023.3236185. Full text in Research Archive
• Hoseinpur Kermani, Arman; Tang, Kai; Ulyashin, Alexander; Palitzch, Wolfram & Safarian, Jafar (2023). Toward the recovery of solar silicon from end-of-life PVs by vacuum refining. Solar Energy Materials and Solar Cells. ISSN 0927-0248. 251. doi: 10.1016/j.solmat.2023.112181. Full text in Research Archive Show summary

  Considering the boom of Si solar cell installation, it is necessary to establish a process for recycling of Si from End-of-life photovoltaics (PVs). Silicon in the PVs is synthetically doped and coated by various elements and hence dedicated methods will be required for recycling of Si, back to the SoG-Si. In this research, recycling of Si from the shredded solar cells is studied by means of vacuum refining process. In this research the rejected solar cells after the firing step are treated by acid etching techniques to remove the Al back layer and the Ag finger on the front side of the cells, providing a product called de-metallized Si fragments. The vacuum refining experiments were carried out on demetallized Si fragments. Results showed the demetallized Si contained presence of P (11.67 ppmw), B (1 ppmw), Ca with up to 0.28 wt%, Ag (96 ppmw) and Sn (136 ppmw), while other metallic impurities were lower. We have shown that Sn, Ag, O, N, and Mg can be removed from the Si melt via short vacuum refining, while a complete removal of Ca and P required longer times compared to the mentioned impurities. Because vacuum refining process is not limited by thermodynamic equilibrium, a full removal of all the volatile impurities at extended times is expected and then this process has a high chance for returning the recovered Si to the solar grade requirements.

• Røyset, Arne Karstein; Kolås, Tore; Nordseth, Ørnulf & You, Chang Chuan (2023). Optical interference coatings for coloured building integrated photovoltaic modules: Predicting and optimising visual properties and efficiency. Energy and Buildings. ISSN 0378-7788. 298. doi: 10.1016/j.enbuild.2023.113517. Full text in Research Archive
• Hansen, Per-Anders Stensby; Sørensen, Silje Holm; Desbois, Nicolas; Gros, Claude P. & Nilsen, Ola (2023). Perylenes, Porphyrins, and Other Large Dye Molecules for Molecular Layer Deposition. Advanced Materials Interfaces. ISSN 2196-7350. doi: 10.1002/admi.202300667. Full text in Research Archive
• Tang, Kai; Rasouli, Azam; Safarian, Jafar; Ma, Xiang & Tranell, Maria Gabriella (2023). Magnesiothermic Reduction of Silica: A Machine Learning Study. Materials. ISSN 1996-1944. 16(11). doi: 10.3390/ma16114098. Full text in Research Archive Show summary

  Fundamental studies have been carried out experimentally and theoretically on the magnesiothermic reduction of silica with different Mg/SiO2 molar ratios (1–4) in the temperature range of 1073 to 1373 K with different reaction times (10–240 min). Due to the kinetic barriers occurring in metallothermic reductions, the equilibrium relations calculated by the well-known thermochemical software FactSage (version 8.2) and its databanks are not adequate to describe the experimental observations. The unreacted silica core encapsulated by the reduction products can be found in some parts of laboratory samples. However, other parts of samples show that the metallothermic reduction disappears almost completely. Some quartz particles are broken into fine pieces and form many tiny cracks. Magnesium reactants are able to infiltrate the core of silica particles via tiny fracture pathways, thereby enabling the reaction to occur almost completely. The traditional unreacted core model is thus inadequate to represent such complicated reaction schemes. In the present work, an attempt is made to apply a machine learning approach using hybrid datasets in order to describe complex magnesiothermic reductions. In addition to the experimental laboratory data, equilibrium relations calculated by the thermochemical database are also introduced as boundary conditions for the magnesiothermic reductions, assuming a sufficiently long reaction time. The physics-informed Gaussian process machine (GPM) is then developed and used to describe hybrid data, given its advantages when describing small datasets. A composite kernel for the GPM is specifically developed to mitigate the overfitting problems commonly encountered when using generic kernels. Training the physics-informed Gaussian process machine (GPM) with the hybrid dataset results in a regression score of 0.9665. The trained GPM is thus used to predict the effects of Mg-SiO2 mixtures, temperatures, and reaction times on the products of a magnesiothermic reduction, that have not been covered by experiments. Additional experimental validation indicates that the GPM works well for the interpolates of the observations.

• Stange, Marit Synnøve Sæverud; Sunde, Tor Olav Løveng; Dahl-Hansen, Runar Plunnecke; Rajput, Kalpna; Graff, Joachim Seland & Belle, Branson Delano [Show all 7 contributors for this article] (2023). High-Rate Epitaxial Growth of Silicon Using Electron Beam Evaporation at High Temperatures. Coatings. ISSN 2079-6412. 13(12). doi: 10.3390/coatings13122030.
• Karsthof, Robert Michael; Frodason, Ymir Kalmann; Galeckas, Augustinas; Weiser, Philip Michael; Zviagin, Vitaly & Grundmann, Marius (2022). Light Absorption and Emission by Defects in Doped Nickel Oxide. Advanced Photonics Research. ISSN 2699-9293. 3(11). doi: 10.1002/adpr.202200138.
• Vukovic, Marija; Høiaas, Ingeborg; Jakovljevic, Marko; Flø, Andreas Svarstad; Olsen, Espen & Burud, Ingunn (2022). Photoluminescence imaging of silicon modules in a string. Progress in Photovoltaics. ISSN 1062-7995. 30(4), p. 436–446. doi: 10.1002/pip.3525.
• Vukovic, Marija; Jakovljevic, Marko; Flø, Andreas Svarstad; Olsen, Espen & Burud, Ingunn (2022). Noninvasive photoluminescence imaging of silicon PV modules in daylight. Applied Physics Letters. ISSN 0003-6951. 120(24). doi: 10.1063/5.0097576.
• Vukovic, Marija; Høiaas, Ingeborg; Jakovljevic, Marko; Flø, Andreas Svarstad; Olsen, Espen & Burud, Ingunn (2022). Outdoor photoluminescence and electroluminescence imaging of photovoltaic silicon modules in a string. AIP Conference Proceedings. ISSN 0094-243X. 2487(1). doi: 10.1063/5.0089308.
• Azarov, Alexander; Bazioti, Kalliopi; Venkatachalapathy, Vishnukanthan; Ponniah, Vajeeston; Monakhov, Eduard & Kuznetsov, Andrej (2022). Disorder-Induced Ordering in Gallium Oxide Polymorphs. Physical Review Letters. ISSN 0031-9007. 128(1). doi: 10.1103/PhysRevLett.128.015704. Full text in Research Archive
• Langørgen, Amanda; Zimmermann, Christian; Frodason, Ymir Kalmann; Verhoeven, Espen Førdestrøm; Weiser, Philip Michael & Karsthof, Robert Michael [Show all 8 contributors for this article] (2022). Influence of heat treatments in H2 and Ar on the E1 center in β-Ga2O3. Journal of Applied Physics. ISSN 0021-8979. 131(115702). doi: 10.1063/5.0083861. Full text in Research Archive
• Titov, A.I.; Karabeshkin, K.V.; Struchkov, A.I.; Nikolaev, V.I.; Azarov, Alexander & Gogova, D.S. [Show all 7 contributors for this article] (2022). Comparative study of radiation tolerance of GaN and Ga2O3 polymorphs. Vacuum. ISSN 0042-207X. 200. doi: 10.1016/j.vacuum.2022.111005. Full text in Research Archive
• Titov, A.I.; Karabeshkin, K.V.; Struchkov, A.I.; Karaseov, P.A. & Azarov, Alexander (2022). Radiation tolerance of GaN: The balance between radiation-stimulated defect annealing and defect stabilization by implanted atoms. Journal of Physics D: Applied Physics. ISSN 0022-3727. 55(17). doi: 10.1088/1361-6463/ac4a38. 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. ISSN 2475-9953. 6(12), p. 1–8. doi: 10.1103/PhysRevMaterials.6.124602. Full text in Research Archive
• Lysne, Hogne; Brakstad, Thomas Vågenes; Kildemo, Morten & Reenaas, Turid Dory (2022). Improved methods for design of PLD and combinatorial PLD films. Journal of Applied Physics. ISSN 0021-8979. 132(12). doi: 10.1063/5.0105298.
• Søndenå, Rune; Weiser, Philip Michael & Monakhov, Eduard (2022). Direct and indirect determination of hydrogen-boron complexes in float-zone silicon wafers. In Brendel, Rolf; Ballif, Christophe; Dubois, Sebastien; Glunz, Stefan; Hahn, Giso; Poortmans, Jeff; Verlinden, Pierre & Weeber, Arthur (Ed.), SiliconPV 2021, The 11th International Conference on Crystalline Silicon Photovoltaics. AIP Publishing (American Institute of Physics). ISSN 978-0-7354-4362-4. doi: 10.1063/5.0089274.
• Imenes, Anne Gerd (2022). PEARL PV Country Reports 2020 - Norway. In Farkas, Istvan; Atsu, Divine; Raghoebarsing, Amrita; Boddaert, Simon; Moser, David & Reinders, Angele (Ed.), PEARL PV Country Reports 2020. University of Twente. ISSN 9789036553629. p. 187–199. doi: 10.3990/1.9789036553629.
• Hammann, Benjamin; Aßmann, Nicole; Weiser, Philip Michael; Kwapil, Wolfram; Niewelt, Tim & Schindler, Florian [Show all 9 contributors for this article] (2022). Hydrogen complexes present after different firing profiles and their influence on LeTID degradation. Conference record of the Photovoltaic Specialists Conference. ISSN 0160-8371. doi: 10.1109/PVSC48317.2022.9938782.
• Warden, Gabriela Kazimiera; Juel, Mari; Gawel, Bartlomiej Adam & Sabatino, Marisa Di (2022). Recent developments on manufacturing and characterization of fused quartz crucibles for monocrystalline silicon for photovoltaic applications. Open Ceramics. 13. doi: 10.1016/j.oceram.2022.100321. Full text in Research Archive Show summary

  The dominating technology of solar cell production today is based on monocrystalline silicon, produced mostly by the Czochralski process. Recently, the solar cell industry, has started to move towards growing larger and better-performing ingots. This triggered a need for crucibles that can withstand longer runtimes with better mechanical properties of high purity to reduce the silicon melt contamination. In this work we present the current state of fused quartz crucibles technology and a summary of the most important literature papers in this field. This review indicates that the characterization of fused quartz crucibles remains a challenge. The existing techniques are often not sufficient for fused quartz glass characterization without optimization. Therefore, further work should be a combination of complementary characterization techniques to be able to assess the properties of the crucible and their interactions, which could result in assessing the best combination of crucible properties.

• Roosloot, Nathan; Neder, Verena; Haug, Halvard; You, Chang Chuan; Polman, A. & Marstein, Erik Stensrud (2021). Broadband angular color stability of dielectric thin film-coated pyramidal textured Si for photovoltaics . Journal of Applied Physics. ISSN 0021-8979. 129. doi: 10.1063/5.0048102. Full text in Research Archive
• 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), p. 1–5. doi: 10.1016/j.tsf.2021.138573. Full text in Research Archive
• 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. Full text in Research Archive
• 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), p. 1–8. doi: 10.1088/2053-1591/ac3e24. Full text in Research Archive
• Bonkerud, Julie; Zimmermann, Christian; Weiser, Philip Michael; Vines, Lasse & Monakhov, Eduard (2021). On the permittivity of titanium dioxide. Scientific Reports. ISSN 2045-2322. 11. doi: 10.1038/s41598-021-92021-5. Full text in Research Archive
• Azarov, Alexander; Venkatachalapathy, Vishnukanthan; Monakhov, Eduard & Kuznetsov, Andrej (2021). Dominating migration barrier for intrinsic defects in gallium oxide: Dose-rate effect measurements. Applied Physics Letters. ISSN 0003-6951. 118(23). doi: 10.1063/5.0051047. Full text in Research Archive
• Azarov, Alexander; Venkatachalapathy, Vishnukanthan; Vines, Lasse; Monakhov, Eduard; Lee, In-Hwan & Kuznetsov, Andrej (2021). Activation energy of silicon diffusion in gallium oxide: Roles of the mediating defects charge states and phase modification. Applied Physics Letters. ISSN 0003-6951. 119(18). doi: 10.1063/5.0070045. Full text in Research Archive
• Frodason, Ymir Kalmann; Zimmermann, Christian; Verhoeven, Espen Førdestrøm; Weiser, Philip Michael; Vines, Lasse & Varley, Joel B (2021). Multistability of isolated and hydrogenated Ga-O divacancies in beta-Ga2O3. PHYSICAL REVIEW MATERIALS. ISSN 2475-9953. 5. doi: 10.1103/PhysRevMaterials.5.025402. Full text in Research Archive
• Røyset, Arne Karstein; Kolås, Tore; Ulyashin, Alexsander G. & Rudzikas, Matas (2021). Efficiency Loss in Coloured Photovoltaics: Estimating the Contribution from Reflection Loss and Absorption Loss, EU PVSEC 2021 – 38th European Photovoltaic Solar Energy Conference and Exhibition. EU PVSEC. ISSN 3-936338-78-7. doi: 10.4229/EUPVSEC20212021-4AV.2.10.
• Olsen, Espen; Mehl, Torbjørn; Stalheim, Helene Eikaas; Juel, Mari; Søndenå, Rune & Burud, Ingunn (2021). The Effect of Pull Speed and Heat Treatment on Thermal Donors in Czhocralski Silicon. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 219(1), p. 1–11. doi: 10.1002/pssa.202100655. Full text in Research Archive Show summary

  In silicon crystals manufactured by the Czochralski method, oxygen is incorporated as a contaminant originating primarily from dissolution of the quartz crucible used to contain the molten silicon feedstock. The oxygen can be found either as interstitials, agglomerates, or as oxide particles. Particular kinds of agglomerates are known to lead to the formation of thermal donors—electronic states in the bandgap of the silicon base material. These can act as sites for recombination of excited charge carriers and are called thermal donors due to their ability to inject two electrons into the conduction band of silicon by thermal excitation, leading to enhanced electrical conductivity. Neither of these features are desirable in Cz-Si manufacture. Herein, the behavior of thermal donors as a function of the pull speed, and the position in the ingot, is investigated. Thermal treatment is provided, first for the formation of thermal donors and then for their removal. The aim is to investigate methods for minimalizing their incorporation in the crystal in the first place and then how they can be removed. Hyperspectral imaging and spectroscopy combined with Fourier-transform infrared spectroscopy are used.

• Zhu, Mengyi; Yue, Shengying; Wu, Guixuan; Tang, Kai; Xu, Yijiang & Safarian, Jafar (2021). P removal from Si by Si-Ca-Al alloying-leaching refining: Effect of Al and the CaAl2Si2 phase. Separation and Purification Technology. ISSN 1383-5866. 271. doi: 10.1016/j.seppur.2021.118675. Full text in Research Archive Show summary

  Phosphorus (P) is a critical impurity in metallurgical-grade Si that needed to be removed for solar-grade Si production. The Si-Ca-Al-P system is one of the most crucial alloy systems for Si refining, where P can be separated by either the Si-Al solvent refining or the Si-Ca alloying-leaching process. In this work, a series of Si-Ca-Al alloys were obtained to investigate the role of alloy composition and the CaAl2Si2 phase in P segregation and separation. The used alumina crucible led to heavy Al contamination and resulted in unexpected Si-Ca-Al alloy compositions. CaAl2Si2 and CaSi2 were found as the main precipitates, and relatively higher P content was detected in the CaAl2Si2 phase. Leaching experiments indicate that P removal degree increases with increasing Ca/Al ratio and increasing total alloying amount (Ca + Al). Effects of alloy composition were further analyzed by statistical methods, which indicates Ca firmly plays a strong, positive, and monotonic role in P removal while no strong attraction between Al and P. Theoretical P removal model for the Si-Ca-Al system was established and in good agreement with measured results. Interaction coefficients of Ca and Al to P were fitted as εP_Ca = 19.2 and εP_Al = 1.8,which further confirms Ca is the essential driving force for P segregation. Finally, the possibility of P solid solution formation was verified by first-principle simulations that both CaAl2Si2 and CaSi2 are able to dissolve P, especially through the Si site, but the CaAl2Si2 phase is more favourable for P dissolution than CaSi2, which explains the reason of the often detected high P content in CaAl2Si2.

• Weiser, Philip Michael; Monakhov, Eduard; Haug, Halvard; Wiig, Marie Syre & Søndenå, Rune (2020). Hydrogen-related defects measured by infrared spectroscopy in multicrystalline silicon wafers throughout an illuminated annealing process. Journal of Applied Physics. ISSN 0021-8979. 127(6). doi: 10.1063/1.5142476. Full text in Research Archive
• Baba, Elbruz Murat; Weiser, Philip Michael; Zayim, Esra Özkan & Karazhanov, Smagul (2020). Temperature-Dependent Photochromic Performance of Yttrium Oxyhydride Thin Films. Physica Status Solidi. Rapid Research Letters. ISSN 1862-6254. 15(1), p. 1–5. doi: 10.1002/pssr.202000459. Full text in Research Archive
• Bonkerud, Julie; Zimmermann, Christian; Herklotz, Frank; Weiser, Philip Michael; Seiffert, Christoph & Verhoeven, Espen Førdestrøm [Show all 8 contributors for this article] (2020). Electrically-active defects in reduced and hydrogenated rutile TiO2. Semiconductor Science and Technology. ISSN 0268-1242. 36(1). doi: 10.1088/1361-6641/abc854. Full text in Research Archive
• Zhu, Mengyi; Azarov, Alexander; Monakhov, Eduard; Tang, Kai & Safarian, Jafar (2020). Phosphorus separation from metallurgical-grade silicon by magnesium alloying and acid leaching. Separation and Purification Technology. ISSN 1383-5866. 240. doi: 10.1016/j.seppur.2020.116614. Full text in Research Archive Show summary

  In this paper, the separation of phosphorus from metallurgical-grade silicon was investigated based on an Mg alloying and HCl leaching approach. Experimental results show that P concentration was reduced from initial 15.1 ppmw to 0.2 ppmw with also large extent removal of metallic impurities by two times Mg alloying-leaching purification. The mechanism of enhanced P separation is clarified owing to the strong affinity between Mg and P, which is validated by SIMS elemental mapping. A two-parameter analytical model was developed to predict the P removal degree based on the variables of alloying metal concentration and interaction coefficient between alloying metal and P. The model is validated with experimental results and the interaction coefficient ε^P_{Mg In Si} was obtained as −10.8. This approach can be applied to model the removal of impurity which follows Gulliver-Scheil solidification from other binary alloying systems. Furthermore, in order to study the effect of applied alloying-leaching operation times, a model was proposed which establishes the mathematical relationships among key processing variables like initial and target P concentrations, the amount of the alloying metal, and the process operation times.

• Azarov, Alexander; Galeckas, Augustinas; Mieszczyński, Cyprian; Hallen, Anders & Kuznetsov, Andrej (2020). Effects of annealing on photoluminescence and defect interplay in ZnO bombarded by heavy ions: Crucial role of the ion dose. Journal of Applied Physics. ISSN 0021-8979. 127. doi: 10.1063/1.5134011. Full text in Research Archive
• Røyset, Arne Karstein; Kolås, Tore & Jelle, Bjørn Petter (2020). Coloured Building Integrated Photovoltaics: Influence on Energy Efficiency. Energy and Buildings. ISSN 0378-7788. 208, p. 1–13. doi: 10.1016/j.enbuild.2019.109623. Full text in Research Archive Show summary

  Building integrated photovoltaics (BIPV) has attracted increased commercial interest in recent years due to a growing focus on efficient utilization of land area and local renewable energy generation. Aesthetic aspects must be considered when photovoltaic panels are applied as building elements. Colours can be added by reflecting some of the sunlight that otherwise could have been utilized for electricity generation. Reflectance spectra of commercial solar cell modules have been measured and analysed. Relative efficiency loss caused by the reflected solar radiation energy has been calculated. The calculated losses in efficiency based on measured spectra have been compared to model spectra with colour coordinates corresponding to RAL colours as well as more idealized monochromatic spectra. The analysis shows that the most important colour parameter affecting loss is the lightness. The second most important parameter is the hue of the colour, with green-yellow colours having the lowest loss, and pink colours resulting in the highest loss, when colours with the same lightness are compared. A Colour Performance Index (CPI) given by luminous reflectance divided by relative loss has been proposed as a figure of merit, thus allowing for a useful comparison of colours with different lightness.

• Olsen, Espen; Helander, Malin Iris; Mehl, Torbjørn & Burud, Ingunn (2020). Spectral Characteristics and Spatial Distribution of Thermal Donors in n-Type Czochralski-Silicon Wafers. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 217(6), p. 1–9. doi: 10.1002/pssa.201900884. Full text in Research Archive Show summary

  In monocrystalline silicon rich in oxygen, thermal donors are formed at temperatures around 450 °C. These are widely accepted to be electrically active oxygen clusters acting as double donors to the conduction band. Exposure to higher temperatures (650 °C) reportedly eliminates them. Herein, a systematic study of the spatial distribution of thermal donor formation and elimination by heat treatment at 450 and 650 °C in commercial n‐type Czochralski‐silicon wafers with high and low content of interstitial oxygen atoms are reported. Hyperspectral imaging techniques with spectral and spatial resolution are used. Thermal donors form at 450 °C in a ring‐like pattern, significantly enhanced in oxygen‐rich material. The results indicate the formation of at least six different donor clusters, leading to a strong, characteristic spectral response upon photoexcitation. The emission related to direct band‐to‐band recombination (1.100 eV) become systematically stronger upon heat treatment at 450 °C. Subsequent treatment at 650 °C rearrange the spectral response into a single, homogenously distributed, broadband emission with peak energy of 0.767 eV. The emission related to band‐to‐band recombination is significantly reduced. A previously studied emission at 0.807 eV (D1) commonly related to impurities is found, providing evidence that this signal is related to the combination of defects and oxygen.

• Reinertsen, Vilde Mari; Weiser, Philip Michael; Frodason, Ymir Kalmann; Bathen, Marianne Etzelmüller; Vines, Lasse & Johansen, Klaus Magnus H (2020). Anisotropic and trap-limited diffusion of hydrogen/deuterium in monoclinic gallium oxide single crystals. Applied Physics Letters. ISSN 0003-6951. 117. doi: 10.1063/5.0027333. Full text in Research Archive Show summary

  The effect of lattice anisotropy on the diffusion of hydrogen (H)/deuterium (2H) in b-Ga2O3 was investigated using secondary ion mass spectrometry (SIMS) and hybrid-functional calculations. Concentration-depth profiles of 2H-implanted single crystals show that 2H can diffuse along the direction perpendicular to the (010) surface at temperatures as low as 300 degC, whereas diffusion along the direction perpendicular to the (-201) surface occurs only around 500 degC. For both directions, the evolution of the 2H concentration–depth profiles after heat treatments can be modeled by trap-limited diffusion. Moreover, the traps can be present in the as-received crystals or created during ion implantation. Comparison of the experimentally obtained binding energy for 2H to the trap (2.3+/-0.2 eV) with the binding energies determined from first-principles calculations suggests that intrinsic point defects (e.g., VGa^ib) or defect complexes (e.g., VGa(2)VO(2)) are excellent candidates for the trap and will play a crucial role in the diffusion of H or 2H in b-Ga2O3.

• Søndenå, Rune & Wiig, Marie Syre (2019). Evolution of the light sensitive defects in high performance multicrystalline silicon wafers. Journal of Applied Physics. ISSN 0021-8979. 125(8). doi: 10.1063/1.5079496. Full text in Research Archive
• Wyller, Guro Marie; Preston, Thomas; Geetha, Anjitha Sarachandra Kumar; Skare, Marte Orderud & Marstein, Erik Stensrud (2019). Combination of a millimeter scale reactor and gas chromatography-mass spectrometry for mapping higher order silane formation during monosilane pyrolysis. Journal of Crystal Growth. ISSN 0022-0248. 530. doi: 10.1016/j.jcrysgro.2019.125305. Full text in Research Archive
• Mehl, Torbjørn; Wyller, Guro Marie; Burud, Ingunn & Olsen, Espen (2019). Increased sensitivity in near infrared hyperspectral imaging by enhanced background noise subtraction. Journal of Spectral Imaging. ISSN 2040-4565. 8(a2), p. 1–8. doi: 10.1255/jsi.2019.a2. Full text in Research Archive
• Mehl, Torbjørn; Luka, Tabea; Lausch, Dominik; Burud, Ingunn & Olsen, Espen (2019). Study of changes in PL spectrum from defects in PERC solar cells with respect to letid. AIP Conference Proceedings. ISSN 0094-243X. 2147. doi: 10.1063/1.5123813. Full text in Research Archive
• Sortland, Øyvind Sunde; Jomâa, Moez; M'hamdi, Mohammed; Øvrelid, Eivind Johannes & Di Sabatino Lundberg, Marisa (2019). Statistical analysis of structure loss in Czochralski silicon growth. AIP Conference Proceedings. ISSN 0094-243X. 2147(1). doi: 10.1063/1.5123875. Full text in Research Archive
• Hoseinpur Kermani, Arman; Tang, Kai & Safarian, Jafar (2019). Kinetic study of vacuum evaporation of elements from ternary melts; case of dilute solution of P in Si-Al melts . Separation and Purification Technology. ISSN 1383-5866. 235. doi: 10.1016/j.seppur.2019.116284. Full text in Research Archive Show summary

  This research is devoted to study phosphorus removal from Si-Al alloys by vacuum refining of the ternary system of dilute solutions of P in Si-20 wt%Al. The experiments were carried out in an induction furnace and after the refining process, the melt was characterized by ICP-MS technique to trace the concentration change of the volatile elements. The experimental results show that P removal from Si-Al-P melts takes place faster compared to Si-P melts and Al evaporates during the vacuum refining as well. The empirical kinetics of P and Al evaporation is discussed and the apparent activation energy for P and Al evaporation from Si-Al melts is obtained as and respectively. Results show that the composition of the melt changes continuously during the refining process due to rapid Al evaporation. In order to investigate the evaporation kinetics of the melt constituents, we developed a numerical approach by applying the Hertz-Knudsen-Langmuir equation for evaporation. This approach can be applied to model the evaporation of the melt constituents in a ternary system whose composition changes during the vacuum refining process. The model is validated with performed experimental results and it can be applied to discuss the effect of temperature, pressure, initial melt composition on the time of vacuum refining.

• Wyller, Guro Marie; Preston, Thomas; Klette, Hallgeir; Mongstad, Trygve & Marstein, Erik Stensrud (2018). Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry. Journal of Crystal Growth. ISSN 0022-0248. 498, p. 315–327. doi: 10.1016/j.jcrysgro.2018.03.024. Full text in Research Archive
• Paudyal, Basant Raj; Imenes, Anne Gerd & Sætre, Tor Oskar (2018). Review of Guidelines for PV Systems Performance and Degradations Monitoring. Proceedings of the European Photovoltaic Solar Energy Conference. ISSN 2196-100X. p. 2037–2050. doi: 10.4229/35thEUPVSEC20182018-6DV.1.32. Full text in Research Archive Show summary

  The recent growth in the PV system deployment and the higher scale of their production make it necessary to pay more attention towards the performance of those systems. System monitoring will provide the status of the systems showing possible degradations and any impending system failures. It also helps with maintaining system quality and ensuring the optimal performance of the system for its lifetime. COST Action PEARL PV aims to formulate such monitoring guidelines for the PV systems applicable for all types of PV technologies, depending upon the end use and duration of the monitoring need. The objective of the present paper is to quantify and provide a review of the guidelines and standards for monitoring of PV systems performance and degradation in practice, and also some results of preliminary work done regarding important information needed to be included in the monitoring guideline.

• Azarov, Alexander; Wendler, Elke; Monakhov, Edouard & Svensson, Bengt Gunnar (2018). Defect stabilization and reverse annealing in ZnO implanted with nitrogen at room and cryogenic temperature. Journal of Applied Physics. ISSN 0021-8979. 123(10). doi: 10.1063/1.5022152. Full text in Research Archive
• Azarov, Alexander; Galeckas, Augustinas; Wendler, Elke; Ellingsen, Josef Gert Åsheim; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Normal and reverse defect annealing in ion implanted II-VI oxide semiconductors. Journal of Applied Physics. ISSN 0021-8979. 122. doi: 10.1063/1.4997847.

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• Honningdalsnes, Erlend Hustad; Riise, Heine Nygard; Kjeldstad, Torunn; Marstein, Erik Stensrud; Stokkan, Gaute & Randle-Boggis, Richard [Show all 10 contributors for this article] (2024). Fordeler med solkraftverk på jord- og skogbruksarealer. Bondebladet. ISSN 0332-8414.
• Øgaard, Mari (2024). Snow losses and snow loss prediction.
• Kolås, Tore (2023). Coloured PV modules based on optical interference coatings.
• Kolås, Tore; Røyset, Arne Karstein; Nordseth, Ørnulf & You, Chang Chuan (2023). Predicting and optimising the performance of coloured solar cell modules based on interference coatings.
• Aßmann, Nicole; Sondenå, Rune; Hammann, Benjamin; Kwapil, Wolfram & Monakhov, Eduard (2023). Reducing Time and Costs of FT-IR Studies of the Ef-fect of SiNx, Dopants, and Emitter on Hydrogen Spe-cies in Si Wafers and Solar Cell Structures.
• Nilsen, Ola (2023). MLD as a Sandbox for Photoactive Hybrid Materials.
• Lysne, Hogne; Brakstad, Thomas Vågenes; Kildemo, Morten & Reenaas, Turid Dory (2023). pyPLD: Phyton library for tailoring thickness and composition of PLD thin films.
• Rosnes, Andreas; Lysne, Hogne; Christiansen, Emil; Reenaas, Turid Dory & Holmestad, Randi (2022). Differentiating Polyamorphous SiO2 by SPED, PDF and Blind Source Separation Algorithm.
• Sund, Steinar Steinkopf & Kolås, Tore (2022). Store fordeler med med solceller på fasaden. Fremtidens Byggenæring (internett). 3, p. 159–162.
• Kolås, Tore (2022). Hva er fremtiden i bygningsintegrerte solceller?
• Imenes, Anne Gerd (2022). The Terawatt challenge: The key role of PV monitoring. Show summary

  As the installation of new PV capacity continues to grow at a rapid rate worldwide, expected to rise from today’s 4% of the global electricity production to almost 15% by 2030, the value of and need for PV monitoring will arguably increase in a corresponding manner. Monitoring data represent the main source of information for the evaluation of economic profitability, system operation strategies, and environmental sustainability of PV power systems. This work will discuss the need for PV monitoring towards the Terawatt transition, including important international work on PV monitoring and databases, standards and guidelines for methods and equipment, data requirements of different user groups, challenges of data access and data quality, further work needed, and consideration of trends for future data collection from various sources of PV monitoring data and as it crosses borderlines with health inspection and diagnostic tools. Examples of the collection and sharing of data as part of collaborative work in the COST Action PEARL PV on Performance and Reliability of PV Systems will be given.

• Strandberg, Rune & Imenes, Anne Gerd (2022). Production estimates for tandem cells using high resolution spectral data.
• Imenes, Anne Gerd (2022). The Terawatt challenge: Why do we need PV monitoring?
• Kolås, Tore; Røyset, Arne Karstein; Nordseth, Ørnulf; You, Chang Chuan; Matusiak, Barbara Szybinska & Xiang, Changying (2021). Colour and gloss of PV-modules for Building Integration.
• Weiser, Philip Michael; Søndenå, Rune & Monakhov, Eduard (2021). Evolution of hydrogen-related defects in float zone-grown silicon wafers under dark annealing: resistivity change vs. FT-IR.
• Selj, Josefine Helene Krogh (2021). Solenergi i Norge. [Internet]. Norsk Klimastilftelse, Klimakvarter.
• Selj, Josefine Helene Krogh (2021). Dette er solenergi. [Internet]. Solklyngen Podcast.
• Selj, Josefine Helene Krogh (2021). Strømprisen til værs. [TV]. NRK.
• Langørgen, Amanda; Karsthof, Robert Michael; Weiser, Philip Michael; Cavani, Olivier; Grasset, Romain & Frodason, Ymir Kalmann [Show all 8 contributors for this article] (2021). Steady-state Photocapacitance Spectroscopy of Intrinsic Defects in Electron-Irradiated β-Ga₂O₃.
• Røyset, Arne Karstein; Kolås, Tore; Ulyashin, Alexsander G. & Rudzikas, Matas (2021). Efficiency Loss in Coloured Photovoltaics: Estimating the Contribution from Reflection Loss and Absorption Loss. Show summary

  Building integrated photovoltaics (BIPV) offers efficient utilisation of land area and local renewable energy generation. Attractive aesthetic aspects and efficient energy generation are important drivers for market acceptance of solar panels as building elements. Coloured modules improve aesthetic aspects at the expense of efficiency loss and increased cost. For a given lightness and colour, a minimum energy loss due to reflected photons is unavoidable. Additional efficiency loss may come from parasitic absorption in the colour providing layers and from unwanted reflection and absorption in the nonvisible near infrared wavelength range. In this paper we present a novel method to identify the different loss contributions: visible reflection loss, near infrared reflection loss, and parasitic absorption loss. The methodology is applied to silicon solar cells where colouration is introduced by interference from a thin indium tin oxide layer on top of the SiNx:H antireflection coating. The method presented here will be a useful tool to optimize efficient colouring of solar cells.

• Lysne, Hogne; Brakstad, Thomas Vågenes; Di Sabatino Lundberg, Marisa; Inzani, Katherine; Kildemo, Morten & Selbach, Sverre Magnus [Show all 8 contributors for this article] (2021). Pulsed laser deposition of doped TiO2 thin films with lateral composition gradients.
• Dahl-Hansen, Runar Plunnecke; Stange, Marit Synnøve Sæverud & Ulyashin, Alexander G. (2021). Stress and microstructure in Si films by high-rate e-beam.
• Stange, Marit Synnøve Sæverud; Dahl-Hansen, Runar Plunnecke; Sunde, Tor Olav Løveng & Ulyashin, Alexander G. (2021). High-Rate Deposition of Epitaxial Silicon by E-beam Evaporation.
• Weiser, Philip Michael (2020). Detecting hydrogen impurities in multicrystalline silicon wafers - synopsis of new results published in the Journal of Applied Physics.
• Kolås, Tore (2019). Efficiency of coloured and transparent PV.
• Lysne, Hogne; Ristola, Markus Joel Benjamin; Sørhaug, Jørgen Andre; Di Sabatino Lundberg, Marisa; Holmestad, Randi & Reenaas, Turid Dory (2019). Tungsten doped silicon for intermediate band solar cells.
• Stalheim, Helene Eikaas; Burud, Ingunn; Olsen, Espen & Mehl, Torbjørn (2019). Detecting oxygen related defects such as thermal donors in Czochralski silicon cross-sections using.
• Hanson, Jens & Chasanidou, Dimitra (2019). The innovation system for solar photovoltaics in Norway: Exploring policy needs.
• Kolås, Tore & Røyset, Arne Karstein (2018). Efficiency of coloured BIPV.
• Wyller, Guro Marie; Preston, Thomas; Klette, Hallgeir; Nordseth, Ørnulf; Skare, Marte Orderud & Marstein, Erik Stensrud (2018). Application of GC-MS Analysis to Monosilane Pyrolysis for Production of Solar Grade Silicon.
• Wyller, Guro Marie; Preston, Thomas; Skare, Marte Orderud; Klette, Hallgeir; Geetha, Anjitha Sarachandra Kumar & Marstein, Erik Stensrud (2018). Exploring thermal pyrolysis of monosilane through gas chromatography-mass spectrometry measurements of higher order silanes.
• Imenes, Anne Gerd (2018). Monitoring of PV System Performance and Degradation.
• Paudyal, Basant Raj; Imenes, Anne Gerd & Sætre, Tor Oskar (2018). Review of Guidelines for PV Systems Performance and Degradations Monitoring. Show summary

  The recent growth in the PV system deployment and the higher scale of their production make it necessary to pay more attention towards the performance of those systems. System monitoring will provide the status of the systems showing possible degradations and any impending system failures. It also helps with maintaining system quality and ensuring the optimal performance of the system for its lifetime. COST Action PEARL PV aims to formulate such monitoring guidelines for the PV systems applicable for all types of PV technologies, depending upon the end use and duration of the monitoring need. The objective of the present paper is to quantify and provide a review of the guidelines and standards for monitoring of PV systems performance and degradation in practice, and also some results of preliminary work done regarding important information needed to be included in the monitoring guideline.

• Stange, Marit Synnøve Sæverud; Sunde, Tor Olav Løveng; Dahl-Hansen, Runar Plunnecke; Azar, Amin Shahrestani; Graff, Joachim Seland & Nørgaard, Jeppe [Show all 7 contributors for this article] (2018). EPITAXIAL GROWTH OF SILICON BY ELECTRON BEAM EVAPORATION DEPOSITION.
• Lysne, Hogne; Hauge, Heidi Sæverud; Nematollahi, Mohammadreza; Di Sabatino Lundberg, Marisa; Holmestad, Randi & Reenaas, Turid Dory (2018). Hyperdoped silicon for intermediate band solar cells.
• Lysne, Hogne; Hauge, Heidi Sæverud; Nematollahi, Mohammadreza; Di Sabatino Lundberg, Marisa; Holmestad, Randi & Reenaas, Turid Dory (2018). Hyperdoped silicon for intermediate band solar cells.
• Azarov, Alexander; Wendler, Elke; Hallen, Anders; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Defect interaction in ZnO investigated by sequential implantation of ions and subsequent annealing.
• Azarov, Alexander & Svensson, Bengt Gunnar (2017). Ion beam modification of wide bandgap semiconductors.
• Azarov, Alexander; Wendler, Elke; Monakhov, Edouard & Svensson, Bengt Gunnar (2017). Effect of pre-existing extended defects on radiation defect dynamics in ZnO implanted with N at room and cryogenic temperatures.
• Monakhov, Edouard; Bathen, Marianne Etzelmüller; Bergum, Kristin; Sky, Thomas Neset & Weiser, Philip Michael (2017). Omvisning for the National Natural Science Foundation of China.
• Safarian, Jafar (2017). Metallurgical processes for solar grade silicon feedstock production .
• Lysne, Hogne; Reenaas, Turid Dory; Sabatino, Marisa Di & Holmestad, Randi (2023). Design and fabrication of (Cr + N) co-doped TiO2 films with a continuous compositional spread. NTNU.
• Larsen, Sigrid Langholm & Imenes, Anne Gerd (2021). Investigation of Outdoor Performance of Silicon Photovoltaic Modules at Different Installation Angles. Universitetet i Agder. Show summary

  The objective of this master thesis is to analyse and compare the performance of two different PV technologies mounted at different tilt angles and orientations. The PV modules are installed on the roof of the J5 building in the University of Agder, located in Grimstad, Norway. The analysis was carried out by comparing 13 months of measured data (from March 2020 to March 2021). The technologies assessed are mono crystalline silicon and poly crystalline silicon, mounted at a tilt angle of 10 deg East/West, 45 deg South and 90 deg South. Data recorded include global and diffuse horizontal irradiance, irradiance in the plane-of-array and other weather parameters, PV module temperature, DC output power, current and voltage for the PV modules. To assess the performance, performance ratio, temperature corrected performance ratio and specific yield has been calculated for all modules on a monthly basis. Results give the DC specific yield for 10 deg tilt modules between 920 - 984 kWh/kWp. The two modules mounted on the 45 deg tilt rack and the BIPV modules all had low data availability due to missing data points. To account for this data are estimated for the missing data point using linear regression. The DC specific yield before estimating data for missing data points for 45 deg are 988 kWh/kWp (mono c-Si 45 deg), 1050 kWh/kWp (poly c-Si 45 deg), 762 kWh/kWp (BIPV normal), and 760 kWh/kWp (BIPV grey). Comparing the two PV technologies at different tilt angles and orientations, there is not detected a substantial difference in performance between the East- and West-facing modules at a 10 deg tilt. The PR for the higher tilted modules are on average slightly better than for the 10 deg tilt modules. The best indication of module performance in the various installation angles are when estimating output power for missing data. From these results the PRDC values of the 10 deg tilt modules are in the range 0.88 - 0.90 (mono c-Si E/W) and 0.88-0.92 (poly c-Si W/E), while for the 45 deg tilt modules the values are 0.92 (mono c-Si) and 0.95 (poly c-Si), and for both the normal and grey BIPV modules at 90 deg tilt the value is 0.94. PVsyst software is used to simulate five mono c-Si modules at 10 deg tilt and East-facing. This is because in the system at UiA five modules are connected in a string to one inverter. Design parameters such as module tilt, orientation, shading and inter-row spacing is defined to obtain as accurate simulation as possible. The results show a good correlation between simulation and calculated results. AC energy output for the simulation was 1436 kWh/year, compared to DC output for the real system at 1451 kWh/year. PVsyst simulation can be used to investigate other installation angles and orientations than the ones analysed in this work.

• Hanson, Jens; Chasanidou, Dimitra & Normann, Håkon Endresen (2021). The Norwegian solar energy innovation system. NTRANS - Norwegian Centre for Energy Transition Strategies. ISSN 978-82-93863-03-8.
• Sortland, Øyvind Sunde; M'hamdi, Mohammed & Jomâa, Moez (2019). Assessment of feature engineering and long short-term memory for structure loss identification from process data in monocrystalline silicon growth by the Czochralski method. Department of Materials Science and Engineering, NTNU. Full text in Research Archive
• Mengyi, Zhu & Safarian, Jafar (2017). Silicon purification by leaching. NTNU. Show summary

  The development of low-cost solar grade silicon (SoG-Si) has received worldwide attentions from both academia and industry in recent. This report is focused on the purification of silicon by acid leaching technique, with emphasis on the acid leaching principle, leaching of doped Si by different alloying refiner metals, and effects of processing parameters on the impurities removal efficiency. Compared with direct leaching of Metallurgical grade silicon (MG-Si), the doping method shows better leaching efficiency, which is depending on the selected refiner metal.

• Hoseinpur, Arman & Safarian, Jafar (2017). Vacuum evaporation of aluminum from molten silicon. NTNU. Show summary

  The elimination of aluminium from silicon binary melts by vacuum refining is studied, a phenomenon occurs in the vacumm refining of silicon for P removal. In this case, the thermodynamics of Si-Al binary melts are studied and the chemical activities and equilibrium partial pressures for the Si and Al components are calculated. Moreover, the total melt vapour pressures for different temperatures are calculated. Experimental trials are done in order to make molten Si-Al alloys and further remove the Al by vacuum. It was found that melting of Si and Al mixtures in graphite crucible is not a proper methodology to make the alloys as there is very high wetting of graphite by Al and its infiltration into the crucible wall and its breakage.

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