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• Strandbakke, Ragnar; Wachowski, Sebastian Lech; Balaguer, Maria; Vines, Lasse; Sky, Thomas Neset & Szpunar, Iga [Show all 12 contributors for this article] (2026). Governing principles of hydration of mixed proton conducting Co-based double perovskites. Nature Communications. 17, p. 1–10. doi: 10.1038/s41467-026-70212-w. Full text in Research Archive Show summary

  Proton ceramic electrochemical cells PCECs hold promise for efficient, sustainable production and use of hydrogen. The positive electrodes are mixed proton conducting perovskites that facilitate water splitting and oxygen reduction, but the factors that determine the protonation are poorly under stood. Here, we establish the governing principles of protonation through a study of hydration of 45 double perovskites with the general formula AIAIICo2O6 δ, having Ba or Ba+Sr on AI and a mix of rare earths (Y and lanthanides Ln =La,Pr,Nd,Sm,Gd,Dy,Tb,Lu)onAII. We show how hydration is coupled to the A-site basicity and disorder as well as population of electron holes in the Co-O bond (Co oxidation state), promoted by a closed or semiclosed Ln 4f shell, i.e., Ln =La,Gd,Lu.

• Müting, Johanna; Bobal, Viktor; Sky, Thomas Neset; Vines, Lasse & Grossner, Ulrike (2020). Lateral straggling of implanted aluminum in 4H-SiC. Applied Physics Letters. ISSN 0003-6951. 116(1). doi: 10.1063/1.5132616. Full text in Research Archive Show summary

  The implantation of aluminum into 4H-SiC is studied using secondary ion mass spectrometry. In particular, two-dimensional concentration profiles are obtained, which allow the investigation of lateral straggling and its dependence on the crystallographic orientation. A high dose, medium energy aluminum implantation is studied in great detail. It shows an asymmetric distribution due to the 4°-off axis growth of the epitaxial layer. The lateral straggling is found to be in the range of several micrometers for a concentration of 1×1015 cm−3, which is contrary to the expectation given by most simulation studies. Implantations performed at different orientations support the idea that lateral straggling highly depends on the particular channeling opening. The Research Council of Norway is acknowledged for the support to the Norwegian Micro- and Nano-Fabrication Facility, NorFab, Project No. 245963.

• Sky, Thomas Neset; Johansen, Klaus Magnus H; Frodason, Ymir Kalmann; Aarholt, Thomas; Riise, Heine Nygard & Prytz, Øystein [Show all 8 contributors for this article] (2019). Diffusion of indium in single crystal zinc oxide: a comparison between group III donors. Semiconductor Science and Technology. ISSN 0268-1242. 34(2), p. 1–6. doi: 10.1088/1361-6641/aafa4c. Full text in Research Archive
• Sky, Thomas Neset; Johansen, Klaus Magnus H; Riise, Heine Nygard; Svensson, Bengt Gunnar & Vines, Lasse (2018). Gallium diffusion in zinc oxide via the paired dopant-vacancy mechanism. Journal of Applied Physics. ISSN 0021-8979. 123(5). doi: 10.1063/1.5000123. Full text in Research Archive Show summary

  Isochronal and isothermal diffusion experiments of gallium (Ga) in zinc oxide (ZnO) have been performed in the temperature range of 900–1050 °C. The samples used consisted of a sputter-deposited and highly Ga-doped ZnO film at the surface of a single-crystal bulk material. We use a novel reaction diffusion (RD) approach to demonstrate that the diffusion behavior of Ga in ZnO is consistent with zinc vacancy (VZn) mediation via the formation and dissociation of GaZnVZn complexes. In the RD modeling, experimental diffusion data are fitted utilizing recent density-functional-theory estimates of the VZn formation energy and the binding energy of GaZnVZn. From the RD modeling, a migration energy of 2.3 eV is deduced for GaZnVZn, and a total/effective activation energy of 3.0 eV is obtained for the Ga diffusion. Furthermore, and for comparison, employing the so-called Fair model, a total/effective activation energy of 2.7 eV is obtained for the Ga diffusion, reasonably close to the total value extracted from the RD-modeling. © 2018 AIP Publishing

• Sky, Thomas Neset; Johansen, Klaus Magnus H; Frodason, Ymir Kalmann; Svensson, Bengt Gunnar & Vines, Lasse (2018). The interaction between lithium acceptors and gallium donors in zinc oxide. Journal of Applied Physics. ISSN 0021-8979. 124(24), p. 1–6. doi: 10.1063/1.5063326. Full text in Research Archive Show summary

  Diffusion of lithium (Li) in uniformly gallium (Ga)-doped monocrystalline bulk Zinc Oxide (ZnO) is studied over a wide temperature range (500 − 1150◦C) and is demonstrated to be dictated by the distribution of Ga. Below 800◦C, the indiffusion of Li from a Li-doped ZnO sputtered film into a n + ZnO bulk yields an abrupt and compensated Li-doped box region with the Li concentration matching the free-electron concentration, in accordance with several previous experimental and theoretical reports. However, experimental observations of Li-diffusion at higher temperatures have not previously been reported. In this study we give a detailed description of a dissociative diffusion mechanism for Li up to 1150◦C. By employing a reaction-diffusion model that accounts for the presence of both Li and Ga, a dissociation energy of 4.6 eV with an attempt frequency of 5×1015s −1 is obtained from the experimental Li diffusion data. This is in excellent agreement with theoretical results for the dissociation of (LiZnGaZn) 0 (4.8 eV) into Li+ i and (GaZnVZn) −, and strongly suggest that this neutral and stable acceptor-donor pair prevails in Li- and Ga-doped ZnO.

• Sky, Thomas Neset; Johansen, Klaus Magnus H; Venkatachalapathy, Vishnukanthan; Svensson, Bengt Gunnar; Tuomisto, Filip & Vines, Lasse (2018). Influence of Fermi level position on vacancy-assisted diffusion of aluminum in zinc oxide. Physical review B (PRB). ISSN 2469-9950. 98(24), p. 245204-1–245204-8. doi: 10.1103/PhysRevB.98.245204. Full text in Research Archive Show summary

  The influence of Fermi level position and annealing ambient on the zinc vacancy VZn generation and Al diffusion is studied in monocrystalline zinc oxide (ZnO). From secondary-ion mass spectrometry and positron annihilation spectroscopy results, a quadratic dependence between the concentrations of VZn and Al is established, demonstrating the Fermi level dependence of the formation of the electrically compensating −2 charge state of VZn in conductive n-type ZnO crystals. In contrast, thermal treatment in the zinc-rich ambient is shown to efficiently reduce the VZn concentration and related complexes. Using a reaction-diffusion model, the diffusion characteristics of Al at different donor background concentrations are fully accounted for by mobile (AlZnVZn)− pairs. These pairs form via the migration and reaction of isolated V2−Zn with the essentially immobile Al+Zn. We obtain a migration barrier for the (AlZnVZn)− pair of 2.4±0.2 eV, in good agreement with theoretical predictions. In addition to strongly alter the shape of the Al diffusion profiles, increasing the donor background concentration also results in an enhanced effective Al diffusivity, attributed to a reduction in the V2−Zn formation energy as the Fermi level position increases.

• Zimmermann, Christian; Bonkerud, Julie; Herklotz, Frank; Sky, Thomas Neset; Hupfer, Alexander & Monakhov, Eduard [Show all 8 contributors for this article] (2018). Influence of annealing atmosphere on formation of electrically-active defects in rutile TiO2. Journal of Applied Physics. ISSN 0021-8979. 123(16), p. 161572-1–161572-8. doi: 10.1063/1.5011136. Full text in Research Archive Show summary

  Electronic states in the upper part of the bandgap of reduced and/or hydrogenated n-type rutile TiO2 single crystals have been studied by means of thermal admittance and deep-level transient spectroscopy measurements. The studies were performed at sample temperatures between 28 and 300 K. The results reveal limited charge carrier freeze-out even at 28 K and evidence the existence of dominant shallow donors with ionization energies below 25 meV. Interstitial atomic hydrogen is considered to be a major contributor to these shallow donors, substantiated by infrared absorption measurements. Three defect energy levels with positions of about 70 meV, 95 meV, and 120 meV below the conduction band edge occur in all the studied samples, irrespective of the sample production batch and the post-growth heat treatment used. The origin of these levels is discussed in terms of electron polarons, intrinsic point defects, and/or common residual impurities, where especially interstitial titanium atoms, oxygen vacancies, and complexes involving Al atoms appear as likely candidates. In contrast, no common deep-level defect, exhibiting a charge state transition in the 200–700 meV range below the conduction band edge, is found in different samples. This may possibly indicate a strong influence on deep-level defects by the post-growth heat treatments employed.

• Grini, Sigbjørn; Ross, Nils; Sky, Thomas Neset; Persson, Clas; Platzer-Björkman, Charlotte & Vines, Lasse (2017). Secondary ion mass spectrometry as a tool to study selenium gradient in Cu2ZnSn(S,Se)4. Physica Status Solidi. C, Current topics in solid state physics. ISSN 1610-1634. 14. doi: 10.1002/pssc.201600187. Full text in Research Archive
• Herklotz, Frank; Johansen, Klaus Magnus H; Galeckas, Augustinas; Sky, Thomas Neset & Svensson, Bengt Gunnar (2016). The influence of Fe impurities on the annealing of OH–Li complexes in ZnO. Physica status solidi (b). ISSN 0370-1972. 253(2), p. 273–278. doi: 10.1002/pssb.201552441. 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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• Aarholt, Thomas; Sky, Thomas Neset; Nguyen, Phuong Dan & Prytz, Øystein (2018). Low-kV EELS band gapmeasurements on indium monolayer structures in ZnO. Full text in Research Archive
• Grini, Sigbjørn; Borgersen, Jon Arthur; Sky, Thomas Neset; Frodason, Ymir Kalmann; Riise, Heine Nygard & Zimmermann, Christian (2018). Omvisning MENA. Full text in Research Archive
• Monakhov, Edouard; Bathen, Marianne Etzelmüller; Bergum, Kristin; Sky, Thomas Neset & Weiser, Philip Michael (2017). Omvisning for the National Natural Science Foundation of China. Full text in Research Archive
• Johansen, Klaus Magnus H; Sky, Thomas Neset; Frodason, Ymir Kalmann; Venkatachalapathy, Vishnukanthan; Svensson, Bengt Gunnar & Vines, Lasse (2017). Tailoring donor diffusion in ZnO by defects and doping. Full text in Research Archive
• Riise, Heine Nygard; Kjeldstad, Torunn; Sky, Thomas Neset & Borgersen, Jon Arthur (2017). MiNaLab-besøk frå Kongsskogen VGS. 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
• Sky, Thomas Neset; Johansen, Klaus Magnus H; Vines, Lasse; Svensson, Bengt Gunnar & Riise, Heine Nygard (2017). Diffusion of Al in ZnO: the interplay with Zn-vacancies. Full text in Research Archive
• Sky, Thomas Neset; Johansen, Klaus Magnus H; Vines, Lasse; Svensson, Bengt Gunnar & Riise, Heine Nygard (2017). Diffusion of Group III Elements in ZnO. Full text in Research Archive
• Vines, Lasse; Sky, Thomas Neset; Johansen, Klaus Magnus H & Svensson, Bengt Gunnar (2017). Self-compensation and the vacancy-dopant pair in highly Al- and Ga-doped ZnO. Full text in Research Archive
• Frodason, Ymir Kalmann; Bergum, Kristin; Sky, Thomas Neset; Ingebrigtsen, Mads Eide; Borgersen, Jon & Ellingsen, Josef Gert Åsheim [Show all 8 contributors for this article] (2017). MiNa-Lab tour highlighting LENS activities. Full text in Research Archive
• Bergum, Kristin; Borgersen, Jon Arthur; Ellingsen, Josef Gert Åsheim; Frodason, Ymir Kalmann; Galeckas, Augustinas & Ingebrigtsen, Mads Eide [Show all 8 contributors for this article] (2017). Omvisning MiNaLab. Full text in Research Archive
• Bathen, Marianne Etzelmüller; Bergum, Kristin; Ellingsen, Josef Gert Åsheim; Grini, Sigbjørn; Sky, Thomas Neset & Aarseth, Bjørn Brevig (2017). Omvisning for Arendal VGS. Full text in Research Archive
• Grini, Sigbjørn; Ross, Nils; Sky, Thomas Neset; Persson, Clas; Platzer-Björkman, Charlotte & Vines, Lasse (2016). Spatial distribution of sodium in Cu2ZnSn(S,Se)4 studied with secondary ion mass spectrometry image depth profiling. Full text in Research Archive
• Grini, Sigbjørn; Ross, Nils; Sky, Thomas Neset; Platzer-Björkman, Charlotte; Persson, Clas & Vines, Lasse (2016). Secondary ion mass spectrometry as a tool to study selenium gradient in Cu2ZnSn(S,Se)4. Full text in Research Archive
• Johansen, Klaus Magnus H; Sky, Thomas Neset; Vines, Lasse; Frodason, Ymir Kalmann; Riise, Heine Nygard & Bjørheim, Tor Svendsen [Show all 7 contributors for this article] (2016). The dynamic interplay between intrinsic defects and shallow donor dopants (Al and Ga) in ZnO. Full text in Research Archive
• Johansen, Klaus Magnus H; Bjørheim, Tor Svendsen; Sky, Thomas Neset; Vines, Lasse & Svensson, Bengt Gunnar (2016). Reaction diffusion simulation - a link between Experiment and DFT. Full text in Research Archive
• Johansen, Klaus Magnus H; Sky, Thomas Neset; Vines, Lasse & Svensson, Bengt Gunnar (2015). Defects, Impurities and Diffusion in ZnO. Full text in Research Archive
• Johansen, Klaus Magnus H; Sky, Thomas Neset; Vines, Lasse; Frodason, Ymir Kalmann; Riise, Heine Nygard & Bjørheim, Tor Svendsen [Show all 7 contributors for this article] (2015). The Interplay between Ga Dopants and Intrinsic Defects in ZnO - Seen from the Diffusion Perspective. Full text in Research Archive
• Johansen, Klaus Magnus H; Sky, Thomas Neset; Herklotz, Frank; Haug, Halvard & Svensson, Bengt Gunnar (2014). IR absorption strength of Ni on Zinc-site in crystalline Zinc Oxid. Full text in Research Archive

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