Augustinas Galeckas

• Kang, Xiaolan; Chaperman, Larissa; Galeckas, Augustinas; Ammar, Souad; Mammeri, Fayna & Norby, Truls [Vis alle 7 forfattere av denne artikkelen] (2021). Water Vapor Photoelectrolysis in a Solid-State Photoelectrochemical Cell with TiO2 Nanotubes Loaded with CdS and CdSe Nanoparticles. ACS Applied Materials & Interfaces. ISSN 1944-8244. 13(39), s. 46875–46885. doi: 10.1021/acsami.1c13047.
• Aarseth, Bjørn Lupton; Granerød, Cecilie Skjold; Galeckas, Augustinas; Azarov, Alexander; Nguyen, Phuong Dan & Prytz, Øystein [Vis alle 7 forfattere av denne artikkelen] (2021). Formation and functionalization of Ge-nanoparticles in ZnO. Nanotechnology. ISSN 0957-4484. 32(50). doi: 10.1088/1361-6528/ac264a. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Karsthof, Robert Michael; Delteil, Aymeric; Sallet, Vincent & Kuznetsov, Andrej [Vis alle 7 forfattere av denne artikkelen] (2021). Resolving Jahn-Teller induced vibronic fine structure of silicon vacancy quantum emission in silicon carbide. Physical review B (PRB). ISSN 2469-9950. 104. doi: 10.1103/PhysRevB.104.045120.
• Olsen, Vegard Skiftestad; Øversjøen, Vetle; Gogova-Petrova, Daniela; Pecz, Bela; Galeckas, Augustinas & Borgersen, Jon Arthur [Vis alle 9 forfattere av denne artikkelen] (2021). ZnSnN2 in Real Space and k-Space: Lattice Constants, Dislocation Density, and Optical Band Gap. Advanced Optical Materials. ISSN 2195-1071. doi: 10.1002/adom.202100015.
• Kang, Xiaolan; Berberidou, Chrysanthi; Galeckas, Augustinas; Bazioti, Kalliopi; Sagstuen, Einar & Norby, Truls Eivind [Vis alle 8 forfattere av denne artikkelen] (2021). Visible Light Driven Photocatalytic Decolorization and Disinfection of Water Employing Reduced TiO2 Nanopowders. Catalysts. ISSN 2073-4344. 11(2). doi: 10.3390/catal11020228.
• 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
• Kjeldstad, Torunn; Thøgersen, Annett; Stange, Marit Synnøve Sæverud; Jensen, Ingvild Julie Thue; Nilsen, Ola & Galeckas, Augustinas [Vis alle 7 forfattere av denne artikkelen] (2020). Selective etching of nanostructured a-Si:Al and its effect on porosity, Al gradient and surface oxidation. Thin Solid Films. ISSN 0040-6090. 702. doi: 10.1016/j.tsf.2020.137982. Fulltekst i vitenarkiv Vis sammendrag

  Nanoporous amorphous silicon (a-Si) with <5 nm cylindrical pores have been fabricated by phase separation of aluminum (Al) and silicon, forming self-assembled Al nanowires (NWs), followed by subsequent removal of Al by wet etching. This work studies the removal process of the Al NWs when using the different etchants HCl, H3PO4, and H2SO4. Total reflectance measurements are used in combination with theoretical modeling to estimate the lateral gradient of Al concentration formed during the etching process. X-ray Photoelectron Spectroscopy is used to show that the choice of Al etching agent has implications for the surface states of the remaining a-Si matrix. We have found that H3PO4 is the most efficient etching agent, while HCl provides a less oxidized a-Si matrix in addition to the least reflective surface. By varying the etching agent, the degree of surface oxidation and shape of Al gradient throughout the film can be tuned.

• Azarov, Alexander; Galeckas, Augustinas; Venkatachalapathy, Vishnukanthan; Mei, Zengxia; Du, Xiaolong & Monakhov, Eduard [Vis alle 7 forfattere av denne artikkelen] (2020). Acceptor complex signatures in oxygen-rich ZnO thin films implanted with chlorine ions. Journal of Applied Physics. ISSN 0021-8979. 128. doi: 10.1063/5.0021089. Fulltekst i vitenarkiv
• Woerle, Judith; Bathen, Marianne Etzelmüller; Prokscha, Thomas; Galeckas, Augustinas; Ayedh, Hussein Mohammed Hussein & Vines, Lasse [Vis alle 7 forfattere av denne artikkelen] (2020). Muon Interaction with Negative-U and High-Spin-State Defects: Differentiating Between C and Si Vacancies in 4H-SiC. Physical Review Applied. ISSN 2331-7019. 14. doi: 10.1103/PhysRevApplied.14.054053. Fulltekst i vitenarkiv
• Karsthof, Robert Michael; Bathen, Marianne Etzelmüller; Galeckas, Augustinas & Vines, Lasse (2020). Conversion pathways of primary defects by annealing in proton-irradiated n-type 4H-SiC. Physical review B (PRB). ISSN 2469-9950. 102(18). doi: 10.1103/PhysRevB.102.184111. Fulltekst i vitenarkiv Vis sammendrag

  The development of defect populations after proton irradiation of n-type 4H-SiC and subsequent annealing experiments is studied by means of deep level transient (DLTS) and photoluminescence spectroscopy. A comprehensive model is suggested describing the evolution and interconversion of irradiation-induced point defects during annealing below 1000 ∘C. The model proposes the EH4 and EH5 traps frequently found by DLTS to originate from the (+/0) charge transition level belonging to different configurations of the carbon antisite-carbon vacancy (CAV) complex. Furthermore, we show that the transformation channel between the silicon vacancy (VSi) and CAV is effectively blocked under n-type conditions, but becomes available in samples where the Fermi level has moved towards the center of the band gap due to irradiation-induced donor compensation. The annealing of VSi and the carbon vacancy (VC) is shown to be dominated by recombination with residual self-interstitials at temperatures of up to 400 ∘C. Going to higher temperatures, a decay of the CAV pair density is reported which is closely correlated to a renewed increase of VC concentration. A conceivable explanation for this process is the dissociation of the CAV pair into separate carbon anitisites and VC defects. Lastly, the presented data supports the claim that the removal of free carriers in irradiated SiC is due to introduced compensating defects and not passivation of shallow nitrogen donors.

• Vasquez, Geraldo Cristian; Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Bazioti, Kalliopi; Johansen, Klaus Magnus H & Maestre, D. [Vis alle 11 forfattere av denne artikkelen] (2020). Strain Modulation of Si Vacancy Emission from SiC Micro- and Nanoparticles. Nano Letters. ISSN 1530-6984. 20(12), s. 8689–8695. doi: 10.1021/acs.nanolett.0c03472. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Coutinho, José & Vines, Lasse (2020). Influence of hydrogen implantation on emission from the silicon vacancy in 4H-SiC. Journal of Applied Physics. ISSN 0021-8979. 127(8). doi: 10.1063/1.5140659. Fulltekst i vitenarkiv Vis sammendrag

  The silicon vacancy (VSi) in 4H-SiC is a room temperature single-photon emitter with a controllable high-spin ground state and is a promising candidate for future quantum technologies. However, controlled defect formation remains a challenge, and, recently, it was shown that common formation methods such as proton irradiation may, in fact, lower the intensity of photoluminescence (PL) emission from VSi as compared to other ion species. Herein, we combine hybrid density functional calculations and PL studies of the proton-irradiated n-type 4H-SiC material to explore the energetics and stability of hydrogen-related defects, situated both interstitially and in defect complexes with VSi, and confirm the stability of hydrogen in different interstitial and substitutional configurations. Indeed, VSi-H is energetically favorable if VSi is already present in the material, e.g., following irradiation or ion implantation. We demonstrate that hydrogen has a significant impact on electrical and optical properties of VSi, by altering the charge states suitable for quantum technology applications, and provide an estimate for the shift in thermodynamic transition levels. Furthermore, by correlating the theoretical predictions with PL measurements of 4H-SiC samples irradiated by protons at high (400 C) and room temperatures, we associate the observed quenching of VSi emission in the case of high-temperature and high-fluence proton irradiation with the increased mobility of Hi, which may initiate VSi-H complex formation at temperatures above 400 C. The important implication of hydrogen being present is that it obstructs the formation of reliable and efficient single-photon emitters based on silicon vacancy defects in 4H-SiC.

• Vasquez, Geraldo Cristian; Johansen, Klaus Magnus H; Galeckas, Augustinas; Vines, Lasse & Svensson, Bengt Gunnar (2020). Optical signatures of single ion tracks in ZnO. Nanoscale Advances. 2(2), s. 724–733. doi: 10.1039/C9NA00677J. Fulltekst i vitenarkiv
• Rauwel, P; Galeckas, Augustinas & Rauwel, Erwan (2019). Time evolution of ZnO-CNT photoluminescence under variable ambient and temperature conditions. IOP Conference Series: Materials Science and Engineering. ISSN 1757-8981. 613(1). doi: 10.1088/1757-899X/613/1/012031. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Müting, Johanna; Ayedh, Hussein Mohammed Hussein; Grossner, Ulrike & Coutinho, José [Vis alle 8 forfattere av denne artikkelen] (2019). Electrical charge state identification and control for the silicon vacancy in 4H-SiC. npj Quantum Information. ISSN 2056-6387. 5(1), s. 1–9. doi: 10.1038/s41534-019-0227-y. Fulltekst i vitenarkiv
• Rauwel, Protima; Galeckas, Augustinas; Ducroquet, Frédérique & Rauwel, Erwan (2019). Selective photocurrent generation in HfO2 and carbon nanotube hybrid nanocomposites under Ultra-Violet and visible photoexcitations. Materials Letters. ISSN 0167-577X. 246, s. 45–48. doi: 10.1016/j.matlet.2019.03.030.
• Frodason, Ymir Kalmann; Johansen, Klaus Magnus H; Galeckas, Augustinas & Vines, Lasse (2019). Broad luminescence from donor-complexed LiZn and NaZn acceptors in ZnO. Physical review B (PRB). ISSN 2469-9950. 100(18). doi: 10.1103/PhysRevB.100.184102. Fulltekst i vitenarkiv
• Schifano, Ramon; Jakiela, R; Galeckas, Augustinas; Kopalko, K; Herklotz, Frank & Johansen, Klaus Magnus H [Vis alle 7 forfattere av denne artikkelen] (2019). Role of intrinsic and extrinsic defects in H implanted hydrothermally grown ZnO. Journal of Applied Physics. ISSN 0021-8979. 126(12). doi: 10.1063/1.5115597. Fulltekst i vitenarkiv
• Olsen, Vegard Skiftestad; Baldissera, Gustavo; Zimmermann, Christian; Granerød, Cecilie Skjold; Bazioti, Kalliopi & Galeckas, Augustinas [Vis alle 11 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv
• Kjeldstad, Torunn; Thøgersen, Annett; Stange, Marit Synnøve Sæverud; Jensen, Ingvild Julie Thue; Monakhov, Eduard & Galeckas, Augustinas (2019). Surface effects and optical properties of self-assembled nanostructured a-Si:Al. Nanomaterials. ISSN 2079-4991. 9(8), s. 1–12. doi: 10.3390/nano9081106. Fulltekst i vitenarkiv
• Ayedh, Hussein Mohammed Hussein; Grigorev, Aleksei; Galeckas, Augustinas; Svensson, Bengt Gunnar & Monakhov, Eduard (2019). Annealing Kinetics of the Interstitial Carbon–Dioxygen Complex in Silicon. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 216(14), s. 1–5. doi: 10.1002/pssa.201800986.
• Kjeldstad, Torunn; Thøgersen, Annett; Stange, Marit Synnøve Sæverud; Azarov, Alexander; Monakhov, Eduard & Galeckas, Augustinas (2019). Monitoring selective etching of self-assembled nanostructured a-Si:Al films. Nanotechnology. ISSN 0957-4484. 30(13), s. 1–5. doi: 10.1088/1361-6528/aafb86. Fulltekst i vitenarkiv
• Almeida Carvalho, Patricia; Thøgersen, Annett; Ma, Quanbao; Wright, Daniel Nilsen; Diplas, Spyridon & Galeckas, Augustinas [Vis alle 12 forfattere av denne artikkelen] (2018). Boron-doping of cubic SiC for intermediate band solar cells: a scanning transmission electron microscopy study. SciPost Physics. ISSN 2542-4653. 5(3). doi: 10.21468/SciPostPhys.5.3.021.
• Ayedh, Hussein Mohammed Hussein; Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Hassan, Jawad U; Bergman, J. P. & Nipoti, Roberta [Vis alle 8 forfattere av denne artikkelen] (2018). Controlling the carbon vacancy in 4H-SiC by thermal processing. ECS Transactions. ISSN 1938-5862. 86(12), s. 91–97. doi: 10.1149/08612.0091ecst.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas; Azarov, Alexander; Vines, Lasse & Kuznetsov, Andrej (2018). Phase stability and strain accumulation in CdO as a function of Cd/O supply during MOVPE synthesis. Superlattices and Microstructures. ISSN 0749-6036. 120, s. 569–577. doi: 10.1016/j.spmi.2018.06.017.
• Galeckas, Augustinas; Almeida Carvalho, Patricia; Ma, Quanbao; Azarov, Alexander; Hovden, Sigurd Slettemark & Thøgersen, Annett [Vis alle 13 forfattere av denne artikkelen] (2018). Optical and microstructural investigation of heavy B-doping effects in sublimation-grown 3C-SiC. Materials Science Forum. ISSN 0255-5476. 924, s. 221–224. doi: 10.4028/www.scientific.net/MSF.924.221. Vis sammendrag

  In this work, a complementary microstructural and optical approach is used to define processing conditions favorable for the formation of deep boron-related acceptor centers that may provide a pathway for achieving an intermediate band behavior in highly B-doped 3C-SiC. The crystallinity, boron solubility and precipitation mechanisms in sublimation-grown 3C-SiC crystals implanted to 1-3 at.% B concentrations were investigated by STEM. The revealed defect formation and boron precipitation trends upon thermal treatment in the range 1100-2000°C have been cross-correlated with the optical characterization results provided by imaging PL spectroscopy. We discuss optical activity of the implanted B ions in terms of both shallow acceptors and deep D-centers, a complex formed by a boron atom and a carbon vacancy, and associate the observed spectral developments upon annealing with the strong temperature dependence of the D-center formation efficiency, which is further enhanced by the presence of implantation-induced defects.

• 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.
• Montero, José ; Galeckas, Augustinas & Karazhanov, Smagul (2018). Photoluminescence Properties of Photochromic Yttrium Hydride Films Containing Oxygen. Physica status solidi (b). ISSN 0370-1972. 255(8). doi: 10.1002/pssb.201800139. Fulltekst i vitenarkiv
• Granerød, Cecilie Skjold; Galeckas, Augustinas; Johansen, Klaus Magnus H; Vines, Lasse & Prytz, Øystein (2018). The temperature-dependency of the optical band gap of ZnO measured by electron energy-loss spectroscopy in a scanning transmission electron microscope. Journal of Applied Physics. ISSN 0021-8979. 123(14), s. 1–6. doi: 10.1063/1.5023316. Fulltekst i vitenarkiv
• Rauwel, Erwan; Galeckas, Augustinas; Soares, M Rosario & Rauwel, Protima (2017). Influence of the Interface on the Photoluminescence Properties in ZnO Carbon-Based Nanohybrids. Journal of Physical Chemistry C. ISSN 1932-7447. 121(27), s. 14879–14887. doi: 10.1021/acs.jpcc.7b03070.
• Ma, Quanbao; Carvalho, Patricia; Galeckas, Augustinas; Azarov, Alexander; Hovden, Sigurd Slettemark & Thøgersen, Annett [Vis alle 13 forfattere av denne artikkelen] (2017). Characterization of B-implanted 3C-SiC for intermediate band solar cells. Materials Science Forum. ISSN 0255-5476. 897, s. 299–302. doi: 10.4028/www.scientific.net/MSF.897.299. Vis sammendrag

  Sublimation-grown 3C-SiC crystals were implanted with B ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 1.3×1017 atoms/cm2 in order to form intermediate band (IB) in 3C-SiC. The samples were then annealed at 1400 °C for 60 min. An anomalous area in the center was observed in the PL emission pattern. The SIMS analysis indicated that the B concentration was the same both within and outside the anomalous area. The buried boron box-like concentration profile can reach ~3×1021 cm-3 in the plateau region. In the anomalous area a broad emission band (possible IB) emerges at around ~1.7-1.8 eV, which may be associated with B-precipitates having a sufficiently high density. Sublimation-grown 3C-SiC crystals were implanted with B ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 1.3×1017 atoms/cm2 in order to form intermediate band (IB) in 3C-SiC. The samples were then annealed at 1400 °C for 60 min. An anomalous area in the center was observed in the PL emission pattern. The SIMS analysis indicated that the B concentration was the same both within and outside the anomalous area. The buried boron box-like concentration profile can reach ~3×1021 cm-3 in the plateau region. In the anomalous area a broad emission band (possible IB) emerges at around ~1.7-1.8 eV, which may be associated with B-precipitates having a sufficiently high density.

• 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.
• Galeckas, Augustinas; Ayedh, Hussein Mohammed Hussein; Bergman, J. Peder & Svensson, Bengt Gunnar (2017). Depth-resolved Carrier Lifetime Measurements in 4H-SiC Epilayers Monitoring Carbon Vacancy Elimination. Materials Science Forum. ISSN 0255-5476. 897, s. 258–261. doi: 10.4028/www.scientific.net/MSF.897.258.
• Rauwel, Protima; Galeckas, Augustinas; Salumaa, Martin; Aasna, Andres; Ducroquet, Frédérique & Rauwel, Erwan Yann (2017). Investigations on new carbon-based nanohybrids combining carbon nanotubes, HfO2 and ZnO nanoparticles. IOP Conference Series: Materials Science and Engineering. ISSN 1757-8981. 175(1). doi: 10.1088/1757-899X/175/1/012064.
• Kjeldstad, Torunn; Thøgersen, Annett; Nilsen, Ola; Monakhov, Edouard & Galeckas, Augustinas (2017). Controllable template approach for ZnO nanowire growth. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. 214(2), s. 1–6. doi: 10.1002/pssa.201600480. Vis sammendrag

  Anodic aluminum oxide (AAO) is an optically transparent material with uniform hexagonal pores, which has widely been used as a template for nanowire growth. This study examines the potential of utilizing commercially available AAO to fabricate sub-10 nm ZnO nanowires by atomic layer deposition. The pore diameter of the AAO framework is reduced by controlled deposition of . Subsequently, ZnO is deposited and ZnO nanowires are obtained. The analysis of structural and optical properties shows that the nanowires are polycrystalline, and exhibit a pronounced near band edge emission. Photoluminescence (PL) measurements are performed to monitor the effect of additional coating with and ZnO, on the optical stability of the AAO. The measurements indicate that the PL is highly influenced by the adsorption and desorption of species from the ambient at the surface. ALD deposition of a thin layer reduces considerably the effect of ambient atmosphere. The layer of facilitates PL characterization of very thin ZnO nanowires.

• Rauwel, Protima; Galeckas, Augustinas; Salumaa, Martin; Ducroquet, Frédérique & Rauwel, Erwan (2016). Photocurrent generation in carbon nanotube/cubic-phase HfO2 nanoparticle hybrid nanocomposites. Beilstein Journal of Nanotechnology. ISSN 2190-4286. 7, s. 1075–1085. doi: 10.3762/bjnano.7.101.
• Azarov, Alexander; Venkatachalapathy, Vishnukanthan; Mei, Zengxia; Liu, Lishu; Du, Xiaolong & Galeckas, Augustinas [Vis alle 9 forfattere av denne artikkelen] (2016). Self-diffusion measurements in isotopic heterostructures of undoped and in situ doped ZnO: Zinc vacancy energetics. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 94. doi: 10.1103/PhysRevB.94.195208.
• Rauwel, Protima; Salumaa, Martin; Aasna, Andres; Galeckas, Augustinas & Rauwel, Erwan Yann (2016). A review of the synthesis and photoluminescence properties of hybrid ZnO and carbon nanomaterials. Journal of Nanomaterials. ISSN 1687-4110. 2016:5320625, s. 1–12. doi: 10.1155/2016/5320625.
• Rauwel, Erwan Yann; Galeckas, Augustinas; Rauwel, Protima; Hansen, Per-Anders; Wragg, David & Nilsen, Ola [Vis alle 7 forfattere av denne artikkelen] (2016). Metal oxide nanoparticles embedded in rare-earth matrix for low temperature thermal imaging applications. Materials Research Express. ISSN 2053-1591. 3(5). doi: 10.1088/2053-1591/3/5/055010.
• Riise, Heine Nygard; Olsen, Vegard Skiftestad; Azarov, Alexander; Galeckas, Augustinas; Sky, Thomas Neset & Svensson, Bengt Gunnar [Vis alle 7 forfattere av denne artikkelen] (2016). Local homoepitaxy of zinc oxide thin films by magnetron sputtering. Thin Solid Films. ISSN 0040-6090. 601, s. 18–21. doi: 10.1016/j.tsf.2015.09.043.
• Ma, Quanbao; Galeckas, Augustinas; Azarov, Alexander; Thøgersen, Annett; Carvalho, Patricia & Wright, Daniel Nilsen [Vis alle 13 forfattere av denne artikkelen] (2016). Boron-implanted 3C-SiC for intermediate band solar cells. Materials Science Forum. ISSN 0255-5476. 858, s. 291–294. doi: 10.4028/www.scientific.net/MSF.858.291. Fulltekst i vitenarkiv Vis sammendrag

  Sublimation-grown 3C-SiC crystals were implanted with 2 atomic percent of boron ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 8.5×1016 atoms/cm2. The samples were then annealed at 1400, 1500 and 1600 °C for 1h at each temperature. The buried boron box-like concentration profile can reach ~2×1021 cm-3 in the plateau region. The optical activity of the incorporated boron atoms was deduced from the evolution in absorption and emission spectra, indicating possible pathway for achieving an intermediate band behavior in boron doped 3C-SiC at sufficiently high dopant concentrations.

• Syväjärvi, Mikael; Ma, Quanbao; Jokubavicius, Valdas; Galeckas, Augustinas; Sun, Jianwu & Liu, Xinyu [Vis alle 18 forfattere av denne artikkelen] (2016). Cubic silicon carbide as a potential photovoltaic material. Solar Energy Materials and Solar Cells. ISSN 0927-0248. 145, s. 104–108. doi: 10.1016/j.solmat.2015.08.029. Fulltekst i vitenarkiv Vis sammendrag

  In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron–hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior. For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior. For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities. We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water

• Schrade, Matthias; Magraso, Anna; Galeckas, Augustinas; Finstad, Terje & Norby, Truls (2016). The Band Gap of BaPrO3 Studied by Optical and Electrical Methods. Journal of The American Ceramic Society. ISSN 0002-7820. 99(2), s. 492–498. doi: 10.1111/jace.13961. Fulltekst i vitenarkiv
• 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), s. 273–278. doi: 10.1002/pssb.201552441.
• Azarov, Alexander; Galeckas, Augustinas; Hallen, Anders; Kuznetsov, Andrej; Monakhov, Edouard & Svensson, Bengt Gunnar (2015). Optical activity and defect/dopant evolution in ZnO implanted with Er. Journal of Applied Physics. ISSN 0021-8979. 118. doi: 10.1063/1.4931423.
• Mayandi, Jeyanthinath; Finstad, Terje; Foss, Steinar; Galeckas, Augustinas & Stange, Marit Synnøve Sæverud (2014). A comparative study of 1.5 μm photoluminescence from (Er, Si) and (Er, Ge) co-sputtered with Al2O3 on Si. Journal of Alloys and Compounds. ISSN 0925-8388. 590, s. 5–8. doi: 10.1016/j.jallcom.2013.12.060. Vis sammendrag

  We present a comparative study of the 1.54lm photoluminescence (PL) from Al2O3:(Er, Si) and Al2O3:(Er, Ge) films co-sputtered on Si substrates using a composite target. The PL yield of Si- and Ge- doped films subjected to different thermal treatment in the range 500–1100 °C is referenced against that of a control Al2O3:(Er) structure. The Er-related emission reaches maximum upon annealing at 700 °C for the Al2O3:(Er, Si) and 500 °C for the Al2O3:(Er, Ge) films, in both cases decreasing at higher annealing tem- peratures. Ge co-doped films are found to be approximately 20 times less luminous than the reference Al2O3:(Er) structure, whereas Si co-doping leads to greatly enhanced emission at 1.54 lm. By adapting energy filtered transmission electron microscopy (EFTEM), the presence of ����2 nm Si nanoclusters was revealed, whereas no indications of Ge clusters or crystals could be observed implying that mere presence of Ge in the Al2O3 matrix can dramatically reduce the luminescence efficiency. We discuss the possible reasons for not forming the Ge nanoclusters in the Al2O3 host and the apparent quenching of the Er- related emission.

• Rauwel, Protima; Galeckas, Augustinas & Rauwel, Erwan Yann (2014). One step synthesis of pure cubic and monoclinic HfO&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt; nanoparticles: Effects of temperature and ambient on the photoluminescent properties. ECS Transactions. ISSN 1938-5862. 64(44), s. 19–28. doi: 10.1149/06444.0019ecst.
• Iwu, Kingsley Odinaka; Galeckas, Augustinas; Diplas, Spyridon; Seland, Frode; Kuznetsov, Andrej & Norby, Truls (2014). Effects of temperature, triazole and hot-pressing on the performance of TiO2 photoanode in a solid-state photoelectrochemical cell. Electrochimica Acta. ISSN 0013-4686. 115, s. 66–74. doi: 10.1016/j.electacta.2013.10.095. Vis sammendrag

  The photocurrent of hydrogen generating solid-state photoelectrochemical cell utilising a polybenzimidazole proton-conducting membrane and gaseous anode reactants has been enhanced by operation at higher temperatures. With a bias of 0 V for example, photocurrent increased from 15 to 30 μA/cm2 on moving from 25 °C to 45 °C. The increase in photocurrent, which was limited by the dehydration of the cell, was shown to have contribution from improved electrode kinetics. Modification of TiO2 surface with triazole, a conjugated heterocyclic compound, led to significant increase in photocurrent up to 4 fold increase at 0 V and 25 °C. This was attributed to improved separation of photogenerated charge carriers, as confirmed by correspondingly increased carrier lifetimes from 50 ns to 90 ns for triazole-modified TiO2. Assembly of the photoelectrochemical cell by hot-pressing induced a ̴ 0.3 eV red shift in optical absorption edge of TiO2, in agreement with a shift of its valence band maximum to higher binding energy.

• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas & Kuznetsov, Andrej (2014). Tunneling in ZnO/ZnCdO quantum wells towards next generation photovoltaic cells. Solar Energy. ISSN 0038-092X. 106, s. 82–87. doi: 10.1016/j.solener.2013.11.032.
• Raeissi, Bahman; Ganagona, Naveengoud; Galeckas, Augustinas; Monakhov, Edouard & Svensson, Bengt Gunnar (2014). PL and DLTS analysis of carbon–related centers in irradiated p–type Cz–Si. Solid State Phenomena. ISSN 1012-0394. 205-206, s. 224–227. doi: 10.4028/www.scientific.net/SSP.205-206.224.
• Li, Jun-Qiang; Mei, Zeng-Xia; Ye, Da-Qian; Liang, Huili; Liu, Lishu & Liu, Yaoping [Vis alle 9 forfattere av denne artikkelen] (2013). Engineering of optically defect free Cu2O enabling exciton luminescence at room temperature. Optical Materials Express. ISSN 2159-3930. 3(12), s. 2072–2077. doi: 10.1364/OME.3.002072.

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• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas; Jensen, Ingvild Julie Thue & Thøgersen, Annett [Vis alle 8 forfattere av denne artikkelen] (2021). EELS and SEM-CL investigations of ZnFe2O4 nanoparticles and iron-decorated inversion domain boundaries in bulk ZnO.
• Azarov, Alexander; Galeckas, Augustinas; Mieszczyński, Cyprian; Hallen, Anders & Kuznetsov, Andrej (2019). Effects of annealing on photoluminescence and defect interplay in ZnO bombarded with heavy ions: crucial role of the ion dose.
• Frodason, Ymir Kalmann; Johansen, Klaus Magnus H; Galeckas, Augustinas & Vines, Lasse (2019). Optical properties of donor-complexed Li_Zn in ZnO .
• Vasquez, Geraldo Cristian; Bazioti, Kalliopi; Galeckas, Augustinas; Johansen, Klaus Magnus H; Granerød, Cecilie Skjold & Nguyen, Phuong Dan [Vis alle 8 forfattere av denne artikkelen] (2019). Luminescent properties of Zn2GeO4 nanoparticles embedded in ZnO.
• Vasquez, Geraldo Cristian; Galeckas, Augustinas; Johansen, Klaus Magnus H; Vines, Lasse & Svensson, Bengt Gunnar (2019). Optical and electrical properties of single ion-tracks in crystalline SiC.
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Müting, Johanna; Ayedh, Hussein Mohammed Hussein; Grossner, Ulrike & Coutinho, J [Vis alle 7 forfattere av denne artikkelen] (2019). Electrical enhancement and switching of single-photon emission from the silicon vacancy in 4H-SiC.
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Müting, Johanna; Ayedh, Hussein Mohammed Hussein; Grossner, Ulrike & Coutinho, José [Vis alle 8 forfattere av denne artikkelen] (2019). Electrical charge-state identification and emission intensity modulation of the silicon vacancy in 4H-SiC.
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Müting, Johanna; Ayedh, Hussein Mohammed Hussein; Grossner, Ulrike & Coutinho, José [Vis alle 7 forfattere av denne artikkelen] (2019). Electrical enhancement and switching of single-photon emission from the silicon vacancy in 4H-Si. Vis sammendrag

  The high-spin ground state and bright single-photon emission of the silicon vacancy (VSi) in 4H-SiC offer exciting possibilities for quantum technology and spintronics applications, especially as both are available at room temperature [1,2]. However, quantum compatibility only exists for the singly negative VSi, and single-photon counts are still too low to realize efficient spin-photon interfaces without resorting to complex nanofabrication methods [3]. Herein, we demonstrate enhanced optical emission from VSi using Schottky barrier diode (SBD) formation, and attribute our findings to increased occupancies of VSi-1.

• Ayedh, Hussein Mohammed Hussein; Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Ul Hassan, Jawad; Bergman, J. P. & Nipoti, Roberta [Vis alle 8 forfattere av denne artikkelen] (2018). Controlling the Carbon Vacancy in 4H-SiC By Thermal Processing.
• Venkatachalapathy, Vishnukanthan; Vajeeston, Ponniah; Galeckas, Augustinas; Vines, Lasse & Kuznetsov, Andrej (2018). Direct and indirect bandgaps of Cadmium Oxide.
• Vasquez, Geraldo Cristian; Johansen, Klaus Magnus H; Galeckas, Augustinas; Vines, Lasse; Svensson, Bengt Gunnar & Maestre, David (2018). Single ion-tracks in crystalline ZnO and their influence on the near band edge luminescence.
• Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Frodason, Ymir Kalmann; Vines, Lasse & Svensson, Bengt Gunnar (2018). Tuning silicon vacancy formation in 4H-SiC via proton irradiation for quantum technology.
• Kjeldstad, Torunn; Thøgersen, Annett; Galeckas, Augustinas; Monakhov, Eduard; Stange, Marit Synnøve Sæverud & Nilsen, Ola (2018). Aluminum nanowires in amorphous silicon.
• Thøgersen, Annett; Stange, Marit Synnøve Sæverud; Galeckas, Augustinas; Nilsen, Ola & Monakhov, Eduard (2018). Aluminum nanowires in amorphous silicon.
• Bathen, Marianne Etzelmüller; Vines, Lasse; Galeckas, Augustinas; Frodason, Ymir Kalmann & Svensson, Bengt Gunnar (2018). Correlating charge state transitions of the Si vacancy to the S1/S2 peaks in DLTS spectra of n-type 4H-SiC.
• Bathen, Marianne Etzelmüller; Vines, Lasse; Galeckas, Augustinas; Frodason, Ymir Kalmann & Svensson, Bengt Gunnar (2018). Charge state transitions of the silicon vacancy in 4H-SiC: Combined DLTS, PL and DFT study.
• Ayedh, Hussein Mohammed Hussein; Azarov, Alexander; Galeckas, Augustinas; Svensson, Bengt Gunnar & Monakhov, Edouard (2017). DLTS study of the interstitial carbon–oxygen complex in proton irradiated p-type Si.
• 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.
• 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.
• Nyborg, Martin; Lindberg, Per; Svensson, Bengt Gunnar; Monakhov, Edouard & Galeckas, Augustinas (2017). DC Magnetron Sputter Deposition of CuxO Thin Films The Effect of Target Power and O2 Flow. Vis sammendrag

  In this study, we report on the effect of target power and O2 flow on DC magnetron sputter deposited CuxO thin films. Target power (Ptar) and oxygen flow (QO2) have been varied in the 80 - 100 W and 12-19 sccm range while keeping all other parameters constant.

• Kjeldstad, Torunn; Thøgersen, Annett; Stange, Marit Synnøve Sæverud; Galeckas, Augustinas & Monakhov, Edouard (2017). Self-assembled aluminium nanowires in silicon.
• Kjeldstad, Torunn; Galeckas, Augustinas; Nilsen, Ola; Azarov, Alexander; Stange, Marit Synnøve Sæverud & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2017). Self-assembly of Al-nanowires in silicon.
• Kjeldstad, Torunn; Thøgersen, Annett; Monakhov, Edouard & Galeckas, Augustinas (2017). Investigation of mesoporous aSi:H with embedded aluminium nanoparticles.
• Kjeldstad, Torunn; Thøgersen, Annett; Monakhov, Edouard & Galeckas, Augustinas (2017). Aluminium nanoparticles embedded in mesoporous aSi:H.
• Thøgersen, Annett; Kjeldstad, Torunn; Jensen, Ingvild Julie Thue; Muntingh, Agnar Georg Peder; Stange, Marit Synnøve Sæverud & Ulyashin, Alexander [Vis alle 9 forfattere av denne artikkelen] (2017). Plasmonic properties of aluminium nanowires in amorphous silicon and inverted silicon nanowires.
• Granerød, Cecilie Skjold; Galeckas, Augustinas; Vines, Lasse; Johansen, Klaus Magnus H & Prytz, Øystein (2017). Temperature-dependency of the ZnO band gap measured by STEM-EELS.
• Granerød, Cecilie Skjold; Galeckas, Augustinas; Johansen, Klaus Magnus H; Vines, Lasse & Prytz, Øystein (2017). The temperature-dependency of the ZnO bandgap studied by STEM-EELS.
• Thøgersen, Annett; Kjeldstad, Torunn; Jensen, Ingvild Julie Thue; Stange, Marit Synnøve Sæverud; Ulyashin, Alexander & Galeckas, Augustinas [Vis alle 9 forfattere av denne artikkelen] (2017). Growing and characterizing self-organizing aluminium nanowires in amorphous silicon.
• Venkatachalapathy, Vishnukanthan; Bakke, Marius Mordal; Galeckas, Augustinas; Vines, Lasse & Kuznetsov, Andrej (2016). Investigation of polar and non-polar Zn(Mg,Cd)O-based Multiple Quantum Wells.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas; Azarov, Alexander & Kuznetsov, Andrej (2016). Structural and optical properties of cubic Cd1-xZnxO.
• Ma, Quanbao; Carvalho, Patricia; Galeckas, Augustinas; Azarov, Alexander; Hovden, Sigurd & Thøgersen, Annett [Vis alle 13 forfattere av denne artikkelen] (2016). Characterization of B-implanted 3C-SiC for intermediate band solar cells .
• Kjeldstad, Torunn; Galeckas, Augustinas; Nilsen, Ola; Azarov, Alexander; Stange, Marit Synnøve Sæverud & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2016). A new silicon nanostructure.
• Kjeldstad, Torunn; Galeckas, Augustinas; Monakhov, Edouard; Nilsen, Ola & Thøgersen, Annett (2016). Controllable template approach for ZnO nanowire growth.
• Ayedh, Hussein Mohammed Hussein; Galeckas, Augustinas; Ma, Quanbao; Bobal, Viktor; Iwamoto, Naoya & Nipoti, R [Vis alle 8 forfattere av denne artikkelen] (2016). Point defects in 4H-SiC.
• Azarov, Alexander; Galeckas, Augustinas; Hallen, Anders; Monakhov, Edouard & Svensson, Bengt Gunnar (2016). Annealing of Er-implanted ZnO: formation/stability of optically active centers, defect evolution and Li behavior.
• Azarov, Alexander; Venkatachalapathy, Vishnukanthan; Mei, Zengxia; Liu, Lishu; Du, Xiaolong & Galeckas, Augustinas [Vis alle 7 forfattere av denne artikkelen] (2015). Zinc vacancy energetics revealed by self-diffusion in isotopic ZnO heterostructures.
• Ma, Quanbao; Galeckas, Augustinas; Azarov, Alexander; Thøgersen, Annett; Carvalho, Patricia & Wright, Daniel Nilsen [Vis alle 13 forfattere av denne artikkelen] (2015). Boron‐implanted 3C‐SiC for intermediate band solar cells.
• Karazhanov, Smagul; Mongstad, TT; Martinsen, Fredrik Aleksander; Amenedo, J. M.; Zayim, E. O. & Mohseni, A. [Vis alle 15 forfattere av denne artikkelen] (2015). Photochromic Materials & Applications.
• Zhan, Wei; Venkatachalapathy, Vishnukanthan; Jensen, Ingvild Julie Thue; Granerød, Cecilie Skjold; Flage-Larsen, Espen & Johansen, Klaus Magnus H [Vis alle 9 forfattere av denne artikkelen] (2015). STEM-EELS Band Gap Measurement in Zn1-XCdXO Thin Films.
• Riise, Heine Nygard; Olsen, Vegard S.; Azarov, Alexander; Galeckas, Augustinas; Monakhov, Edouard & Svensson, Bengt Gunnar (2015). Structural Characteristics of Homoepitaxial Radio Frequency Magnetron Sputter Deposited Zinc Oxide Thin Films.
• Rauwel, Erwan; Galeckas, Augustinas; Wragg, David Stephen; Nilsen, Ola & Fjellvåg, Helmer (2014). The Electrochemical Society, find out more The Electrochemical Society, find out more ALD Applied to Conformal Rare-Earth Coating of ZnO Nanoparticles for Low Temperature Thermal Imaging Applications. ECS Transactions. ISSN 1938-5862. doi: 10.1149/06409.0023ecst.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas & Kuznetsov, Andrej (2014). Interplay of Structural and Optical properties in CdO.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas; Azarov, Alexander & Kuznetsov, Andrej (2014). Investigation of Ga-Doping Effects in ZnO.
• Venkatachalapathy, Vishnukanthan; Azarov, Alexander; Galeckas, Augustinas & Kuznetsov, Andrej (2014). Synthesis and Characterization of Highly Conductive and Optically Transparent Al-Doped Zn1-xMgxO Films.
• Riise, Heine Nygard; Schifano, Ramon; Galeckas, Augustinas; Azarov, Alexander; Monakhov, Edouard & Svensson, Bengt Gunnar (2014). A comparative study of annealing effects on Si and Al doped ZnO.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas & Kuznetsov, Andrej (2013). Band gap engineering in ZnO for Solar energy harvesting - Multiple Quantum Well Solar Cells.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas & Kuznetsov, Andrej (2013). Strained ZnCdO/ZnO multiple quantum well structures.
• Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas & Kuznetsov, Andrej (2013). CdO-ZnO Multiple Quantum Wells as Components for Next Generation Solar Cells.

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