Phuong Dan Nguyen

• García Fernández, Javier; Kjeldby, S.B.; Zeng, L.J.; Azarov, Alexander; Pokle, Anuj & Nguyen, Phuong Dan [Vis alle 10 forfattere av denne artikkelen] (2024). In situ atomic-resolution study of transformations in double polymorph ?/ß-Ga<inf>2</inf>O<inf>3</inf> structures. Materials Advances. ISSN 2633-5409. doi: 10.1039/d3ma01011b.
• Leon_Valido, Dario Alejandro; Elgvin, Cana; Nguyen, Phuong Dan; Prytz, Øystein; Hage, Fredrik Sydow & Berland, Kristian (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Physical review B (PRB). ISSN 2469-9950. 109(11). doi: 10.1103/PhysRevB.109.115153.
• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; García Fernández, Javier; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Vis alle 9 forfattere av denne artikkelen] (2023). Optical properties of ZnFe2O4 nanoparticles and Fe-decorated inversion domain boundaries in ZnO. Nanoscale Advances. 5(7), s. 2102–2110. doi: 10.1039/d2na00849a. Fulltekst i vitenarkiv Vis sammendrag

  The maximum efficiency of solar cells utilizing a single layer for photovoltaic conversion is given by the single junction Shockley–Queisser limit. In tandem solar cells, a stack of materials with different band gaps contribute to the conversion, enabling tandem cells to exceed the single junction Shockley–Queisser limit. An intriguing variant of this approach is to embed semiconducting nanoparticles in a transparent conducting oxide (TCO) solar cell front contact. This alternative route would enhance the functionality of the TCO layer, allowing it to participate directly in photovoltaic conversion via photon absorption and charge carrier generation in the nanoparticles. Here, we demonstrate the functionalization of ZnO through incorporation of either ZnFe2O4 spinel nanoparticles (NPs) or inversion domain boundaries (IDBs) decorated by Fe. Diffuse reflectance spectroscopy and electron energy loss spectroscopy show that samples containing spinel particles and samples containing IDBs decorated by Fe both display enhanced absorption in the visible range at around 2.0 and 2.6 eV. This striking functional similarity was attributed to the local structural similarity around Fe-ions in spinel ZnFe2O4 and at Fe-decorated basal IDBs. Hence, functional properties of the ZnFe2O4 arise already for the two-dimensional basal IDBs, from which these planar defects behave like two-dimensional spinel-like inclusions in ZnO. Cathodoluminescence spectra reveal an increased luminescence around the band edge of spinel ZnFe2O4 when measuring on the spinel ZnFe2O4 NPs embedded in ZnO, whereas spectra from Fe-decorated IDBs could be deconvoluted into luminescence contributions from bulk ZnO and bulk ZnFe2O4.

• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Karlsen, Ole Bjørn; Vines, Lasse & Prytz, Øystein (2022). Formation of γ-Ga2O3 by ion implantation: Polymorphic phase transformation of β-Ga2O3. Applied Physics Letters. ISSN 0003-6951. 121(19). doi: 10.1063/5.0120103. Fulltekst i vitenarkiv
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Venkatachalapathy, Vishnukanthan; Mikšová, R. & MacKová, A. [Vis alle 9 forfattere av denne artikkelen] (2022). Radiation-induced defect accumulation and annealing in Si-implanted gallium oxide. Journal of Applied Physics. ISSN 0021-8979. 131(12). doi: 10.1063/5.0083858. Fulltekst i vitenarkiv
• 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
• Granerød, Cecilie Skjold; Aarseth, Bjørn Lupton; Nguyen, Phuong Dan; Bazioti, Kalliopi; Azarov, Alexander & Svensson, Bengt Gunnar [Vis alle 8 forfattere av denne artikkelen] (2019). Structural and optical properties of individual Zn2GeO4 particles embedded in ZnO. Nanotechnology. ISSN 0957-4484. 30(22), s. 1–6. doi: 10.1088/1361-6528/ab061c. Fulltekst i vitenarkiv
• Bundli, Silje; Dhak, Prasanta; Jensen, Martin; Gunnæs, Anette Eleonora; Nguyen, Phuong Dan & Fjellvåg, Helmer [Vis alle 7 forfattere av denne artikkelen] (2019). Controlled alloying of Pt-Rh nanoparticles by the polyol approach. Journal of Alloys and Compounds. ISSN 0925-8388. 779, s. 879–885. doi: 10.1016/j.jallcom.2018.11.301.
• Jensen, Ingvild Julie Thue; Gorantla, Sandeep Madhukar; Løvvik, Ole Martin; Gan, Jiantuo; Nguyen, Phuong Dan & Monakhov, Edouard [Vis alle 9 forfattere av denne artikkelen] (2017). Interface phenomena in magnetron sputtered Cu2O/ZnO heterostructures. Journal of Physics: Condensed Matter. ISSN 0953-8984. 29(43). doi: 10.1088/1361-648X/aa8799. Fulltekst i vitenarkiv
• Nguyen, Phuong Dan; Gunnæs, A. E.; Sunding, M. F. & Olsen, Arne (2014). Heterogeneous nucleation and growth of CrSi 2 in sputtered thin films of silicon/silicon nitride. Thin Solid Films. ISSN 0040-6090. doi: 10.1016/j.tsf.2014.01.080.
• Nguyen, Phuong Dan; Gunnæs, Anette Eleonora; Sunding, Martin Fleissner & Olsen, Arne (2014). Heterogeneous nucleation and growth of CrSi2 in sputtered thin films of silicon/silicon nitride. Thin Solid Films. ISSN 0040-6090. 556, s. 200–205. doi: 10.1016/j.tsf.2014.01.080.
• Nguyen, Phuong Dan; Kepaptsoglou, D.M.; Erni, Rolf; Ramasse, Q.M. & Olsen, Arne (2013). Quantum Confinement in Germanium Quantum Dots Observed by Electron Energy-Loss Spectroscopy. Microscopy and Microanalysis. ISSN 1431-9276. doi: 10.1017/s1431927613009422.
• Nguyen, Dan Phuong; Kepaptsoglou, Despoina Maria; Ramasse, Q.M. & Olsen, Arne (2012). Direct observation of quantum confinement of Si nanocrystals in Si-rich nitrides. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 85(8). doi: 10.1103/PhysRevB.85.085315.
• Nguyen, Phuong Dan; Olsen, Arne; Kepaptsoglou, D.M. & Ramasse, Q.M. (2012). Quantum confinement of Si nanocrystals in Si-rich nitrides. Microscopy and Microanalysis. ISSN 1431-9276. doi: 10.1017/s1431927612010975.
• Nguyen, Phuong Dan; Kepaptsoglou, D.M.; Ramasse, Q.M. & Olsen, Arne (2012). Direct observation of quantum confinement of Si nanocrystals in Si-rich nitrides. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. doi: 10.1103/physrevb.85.085315.
• Nguyen, Phuong Dan; Kepaptsoglou, D.M.; Ramasse, Q.M.; Sunding, M. F.; Vestland, L.O. & Finstad, T. G. [Vis alle 7 forfattere av denne artikkelen] (2012). Impact of oxygen bonding on the atomic structure and photoluminescence properties of Si-rich silicon nitride thin films. Journal of Applied Physics. ISSN 0021-8979. doi: 10.1063/1.4756998.
• Nguyen, Phuong Dan; Kepaptsoglou, D.M.; Erni, Rolf; Ramasse, Q.M. & Olsen, Arne (2012). Quantum confinement of volume plasmons and interband transitions in germanium nanocrystals. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. doi: 10.1103/physrevb.86.245316.
• Kepaptsoglou, Despoina Maria; Erni, R; Ramasse, Q.M.; Olsen, Arne & Nguyen, Dan Phuong (2012). Quantum confinement of volume plasmons and interband transitions in germanium nanocrystals. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 86(24). doi: 10.1103/PhysRevB.86.245316.

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• Kjeldby, Snorre Braathen; García Fernández, Javier; Nguyen, Phuong Dan; Prytz, Øystein & Vines, Lasse (2023). Implantation for polymorphic transformation in Ga2O3: thermal evolution and luminescence. Vis sammendrag

  Dette foredraget presenterer ioneimplantasjonindusert fasetransformasjon i galliumoksid, Ga2O3, fra beta-fasen til gamma-fasen. Den siste tiden har det vært utbredt vitenskaplig interesse i denne transformasjonen, som, basert på tilgjengelige data, ser ut til å være uavhengig av det implanterte speciet. Utover å presentere forsøk som fastslår den termiske stabiliteten til gamma-fasen, opp til 500 eller 700 grader Celsius avhengig av implantasjonsparametre, presenterer vi her også de første luminesensmålingene på slike prøver med høy romlig oppløsning, hovedsaklig fra prøver implantert med germanium, med støttende resultater fra nikkelimplanterte prøver. Både intrinsisk luminesens, fra selvlokaliserte hull og intrinsiske defekter, og ekstrinsisk luminesens fra krom ble studert. Foredraget bidrar til å klargjøre ikke bare strukturen men også egenskapene til fasetransformerte lag i galliumoksid fra ioneimplantasjon.

• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Vis alle 9 forfattere av denne artikkelen] (2023). Optical properties and structure relationship in ZnO:Fe with inversion domain boundaries and ZnFe2O4/ZnO heterostructures.
• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Azarov, Alexander; Pokle, Anuj; Nguyen, Phuong Dan & Vines, Lasse [Vis alle 8 forfattere av denne artikkelen] (2023). Polymorph engineering and radiation tolerance in β-Ga2O3.
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Garcia Fernandez, Javier; Venkatachalapathy, Vishnukanthan & Mikšová, Romana [Vis alle 10 forfattere av denne artikkelen] (2022). Structure and luminescence properties of Si-implanted β-Ga2O3.
• Kjeldby, Snorre Braathen; Azarov, Alexander; Nguyen, Phuong Dan; Venkatachalapathy, Vishnukanthan; Mikšová, Romana & Macková, Anna [Vis alle 10 forfattere av denne artikkelen] (2022). Structural Transformation of β-Ga2O3 through Si-implantation.
• Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Garcia Fernandez, Javier; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Vis alle 9 forfattere av denne artikkelen] (2022). Optical properties of Fe-decorated inversion domain boundaries and embedded spinel zinc ferrite nanoparticles in zinc oxide.
• Garcia Fernandez, Javier; Kjeldby, Snorre Braathen; Nguyen, Phuong Dan; Haug, Kristian; Galeckas, Augustinas & Jensen, Ingvild Julie Thue [Vis alle 9 forfattere av denne artikkelen] (2022). Structural and optical investigation of Fe-ZnO nanoarchitectures: from inversion domain boundaries to ZnO/ZnFe2O4 heterostructure.
• Elgvin, Cana; Kjeldby, Snorre Braathen; Both, Kevin Gregor; Nguyen, Phuong Dan & Prytz, Øystein (2022). Optical Properties of Zinc Ferrite Nanoparticles Embedded in Zinc Oxide Thin Films Investigated by STEM, EELS and CL.
• 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.
• Elgvin, Cana; Nguyen, Phuong Dan; Both, Kevin Gregor; Vines, Lasse & Prytz, Øystein (2021). Crystallographically oriented ZnFe2O4 nanoparticles in ZnO thin films .
• 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.
• Haug, Kristian; Nguyen, Phuong Dan; Karlsen, Ole Bjørn; Aarholt, Thomas; Bazioti, Kalliopi & Prytz, Øystein (2019). Zinc ferrite spinel embedded in ZnO matrix for solar applications.
• Nguyen, Phuong Dan; Granerød, Cecilie Skjold; Aarseth, Bjørn Lupton; Bazioti, Kalliopi; Azarov, Alexander & Svensson, Bengt Gunnar [Vis alle 8 forfattere av denne artikkelen] (2019). Structural and optical properties of individual Zn2GeO4 particles embedded in ZnO.
• Prytz, Øystein; Karlsen, Ole Bjørn; Nguyen, Phuong Dan; Carvalho, Patricia A. & Lundell, Martin Egge (2018). Illustrert vitenskap. [Tidsskrift]. Bilder.
• Aarholt, Thomas; Sky, Thomas Neset; Nguyen, Phuong Dan & Prytz, Øystein (2018). Low-kV EELS band gapmeasurements on indium monolayer structures in ZnO.
• Granerød, Cecilie Skjold; Zhan, Wei; Aarseth, Bjørn Brevig; Nguyen, Phuong Dan; Johansen, Klaus Magnus H & Vines, Lasse [Vis alle 7 forfattere av denne artikkelen] (2016). Bandgap measurements by STEM-EELS.
• Granerød, Cecilie Skjold; Nguyen, Phuong Dan; Gunnæs, Anette Eleonora & Prytz, Øystein (2016). The Structure Physics group.
• Lervik, Adrian; Bjørheim, Tor Svendsen; Nguyen, Phuong Dan; Diplas, Spyridon; Haugsrud, Reidar & Gunnæs, Anette Eleonora (2016). Chemical and Structural Investigations of Grain Boundaries in Y-Doped BaZrO3.
• Granerød, Cecilie Skjold; Nguyen, Phuong Dan; Zhan, Wei; Monakhov, Edouard & Prytz, Øystein (2015). Band gap measurements by STEM-EELS.
• Granerød, Cecilie Skjold; Nguyen, Phuong Dan; Zhan, Wei; Monakhov, Edouard & Prytz, Øystein (2015). High Energy Resolution EELS on ZnO/Cu2O Heterostructures.
• Roaldset, Elen; Bering, Dag; Aerts, Maarten & Nguyen, Phuong Dan (2014). Kaolinite Group minerals from weathered anorthosite, SW Norway. Vis sammendrag

  31 Nordic Geological Winter Meeting,Jan. 8-10, 2014. Abstract volume p. 72. Roaldset et al: Investigations of the kaolinite group minerals from in-situ weathered anorthosite at Dydland near Flekkefjord, SW Norway, show the presence of the polymorphs nacrite and/or dickite in addition to kaolinite. The kaolin deposits here were exploited for industrial purposes in the years 1898-1904. Reusch (1901) described the isolated areas of kaolinitic material and interpreted them to be of hydrothermal origin, while they, in the light of today’s geological knowledge, most probably are remnants of preglacial weathering. The basement rocks here are of Proterozoic age, while the time of the deep weathering is difficult to assess. Through geologic eras the region has been subjected to subsidence, sedimentation, uplift, fluvial and glacial erosion. In the Cenozoic the region experienced extensive tectonic movements. The Dydland site is close to the Skagerrak coast and lies about 100 m a.s.l. Detailed mineralogical studies of the Dydland kaolin by XRD, SEM-EDS, TEM and IR are in progress. Verification and characteristics of the kaolinite, dickite and/or nacrite will be presented and discussed in relation to origin and age. Diagenetic mineral transformations may indirectly give information about thickness of a post-weathering sedimentary cover later removed by erosion. Reference: Reusch, H. (1901) En forekomst af kaolin og ildfast ler ved Dydland nær Flekkefjord. Norges geologiske undersøkelse, 32, 99-103.

• Vikne, Martin Schønning; Prytz, Øystein; Nguyen, Phuong Dan & Bergum, Kristin (2022). TEM Characterization of ZnOxNy for Tandem Solar Cell Applications. Universitetet i Oslo.
• Bergli, Jørgen; Prytz, Øystein; Nguyen, Phuong Dan & Karlsen, Ole Bjørn (2021). Solid state precipitation of spinels in zinc oxide - A microstructure study. Universitetet i Oslo. Vis sammendrag

  In this work we have investigated the possibility for solid state precipitation of spinel crystals in zinc oxide by separate addition of three different dopant elements. These dopant elements were iron, antimony and vanadium, and were generally introduced as oxide powders. The dopant compounds were mixed with zinc oxide using a powder synthesis route, where the annealing temperature was mostly kept below the solidus temperature in the given system. Some experiments were also performed using a single crystal of zinc oxide embedded in iron oxide and zinc oxide powders. These samples are referred to as diffusion couples. The characterization of samples was carried out by adopting several observation methods. That is light microscopy, x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and scanning transmission electron microscopy. This variety of methods enabled complementary information to be obtained. It was found that the zinc oxide – iron system displays the most promising features in regard to precipitating spinels crystals in the zinc oxide matrix. This property is attributed to a highly temperature dependent solid solubility of iron in zinc oxide. Observations made in this system indicate that two different spinel forming mechanisms are possible. One includes a high solute iron concentration in zinc oxide and consequently precipitation during cooling of the sample. In the other route a second annealing step is added to promote the precipitation from a somewhat low iron concentration in the zinc oxide matrix. The physical appearance of the precipitates was different depending on precipitation route, however the same orientation relationship with adjacent zinc oxide grains/matrix was found for both spinel precipitates. In addition, iron rich inversion domain boundaries were seen in the single crystal. These were explored, and it was found that the spacing between the domains matched the iron concentration profile in the same region. The transition from inversion domain boundaries to spinel grains was probed to understand nucleation mechanisms for both features. In the two other systems, antimony and vanadium doped zinc oxide, no precipitations were found. However, it was found that zinc oxide had low and more or less constant solid solubility when temperature was varied in these systems, which is assumed to be a determining factor in limiting the possibility for precipitations. Therefore, attempts were done in the zinc oxide – vanadium system to increase the solubility. However, despite interesting synthesis development, we were not able to increase the solid solubility. In the zinc oxide – antimony system we show that etching of surfaces could be a way to render inversion domain boundaries visible in scanning electron microscopes. We also confirm the volatility of antimony by the use of x-ray diffraction and energy dispersible spectroscopy.

• Wiken Langfeldt, Sindre; Prytz, Øystein; Karlsen, Ole Bjørn & Nguyen, Phuong Dan (2015). Syntese og karakterisering av termoelektriske halv-Heusler materialer av typen (Ti,Zr,Hf)NiSn. Universitetet i Oslo.
• Nguyen, Dan Phuong (2013). Synthesis and characterisation of sputtered thin films for renewable energy purposes. Det matematisk naturvitenskapelige fakultet.

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