Simon Phillip Cooil

• Åsland, Anna Cecilie; Bakkelund, Johannes; Cooil, Simon Phillip; Røst, Håkon; Hu, Jinbang & Vescovo, E. [Vis alle 9 forfattere av denne artikkelen] (2025). Overcoming the challenges of accessing topological hallmarks in Sb(112). Electronic Structure. 7(3). doi: 10.1088/2516-1075/adf384. Fulltekst i vitenarkiv Vis sammendrag

  Sb is topologically non-trivial and semi-metallic, but differs from many topological semi-metals because of its continuous band gap. By measuring its (112) surface using angle- and spin-resolved photoemission spectroscopy, Sb(112) was shown to have 1D spin-polarised surface states resembling those on vicinal Bi surfaces and many topological insulators and topological semi-metals. The shape and spin-polarisation of the measured features and the calculated bands agreed. However, the measured features had a slightly steeper energy dispersion and different Fermi-momenta than the calculated bands. Both theoretical and experimental methods were necessary when determining the topology of Sb(112). The presence of projected bulk states near the Fermi-level and varying surface localisation of the electronic states meant it was challenging to deduce the topology of Sb(112) from the number of bands crossing the Fermi-level or a continuous contour in the bulk band gap. Ultimately, the calculations and measurements suggest that there are topological surface states on the Sb(112) surface.

• Kjeldby, Snorre Braathen; Nielsen, Dina Marie; Cooil, Simon Phillip; Frodason, Ymir Kalmann; Zacharaki, Eirini & Lee, In Hwan [Vis alle 10 forfattere av denne artikkelen] (2025). Tuning Properties of II-IV-Nitrides for Optoelectronic Applications. Advanced Optical Materials. 13(36). doi: 10.1002/adom.202502634. Fulltekst i vitenarkiv Vis sammendrag

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

• Strand, Frode Sneve; Cooil, Simon Phillip; Campbell, Quinn T.; Flounders, John J.; Røst, Håkon & Åsland, Anna Cecilie [Vis alle 16 forfattere av denne artikkelen] (2025). Direct Observation of 2DEG States in Shallow Si:Sb δ-Layers. Journal of Physical Chemistry C. ISSN 1932-7447. 129(2), s. 1339–1347. doi: 10.1021/acs.jpcc.4c07331. Fulltekst i vitenarkiv Vis sammendrag

  We investigate the electronic structure of high-density layers of Sb dopants in a silicon host, so-called Si:Sb δ-layers. We show that, in spite of the known challenges in producing highly confined Sb δ-layers, sufficient confinement is created such that the lowest conduction band states (Γ states, studied in depth in other silicon δ-layers), become occupied and can be observed using angle-resolved photoemission spectroscopy. The electronic structure of the Si:Sb δ-layers closely resembles that of Si:P systems, where the observed conduction band is near-parabolic and slightly anisotropic in the k∥ plane. The observed Γ state extends ∼1 nm in the out-of-plane direction, which is slightly wider than the 1/3 monolayer thick dopant distribution. This is caused by a small segregation of the dopant layer, which is nevertheless minimal when comparing with earlier published attempts. Our results serve to demonstrate that Sb is still a feasible dopant alternative for use in the semiconductor δ-layer platform, providing similar electronic functionality to Si:P systems. Additionally, it has the advantages of being less expensive, more controllable, safer to handle, and more compatible with industrial patterning techniques. Si:Sb is therefore a viable platform for emerging quantum device applications.

• Åsland, Anna Cecilie; Cooil, Simon Phillip; Mamedov, Damir; Røst, Håkon; Bakkelund, Johannes & Li, Z. [Vis alle 8 forfattere av denne artikkelen] (2024). Initial stages of water absorption on CeO2 surfaces at very low temperatures for understanding anti-icing coatings. Materials Research Express. 11(11). doi: 10.1088/2053-1591/ad913e. Fulltekst i vitenarkiv Vis sammendrag

  Anti-icing coatings are intended to prevent ice formation on surfaces, minimising the risk of surface-related damage and also reducing ice-related hazards in society. We demonstrate the usefulness of x-ray photoelectron spectroscopy (XPS) as a tool for investigating the anti-icing properties of surfaces simultaneously with their chemical composition by looking at the initial stages of water absorption on the surface of CeO2 coatings. CeO2 coatings are robust, hydrophobic, and transmit light, thus they are suitable for a range of applications. In this work, CeO2 coatings were grown by sputter deposition and transferred to an ultra-high vacuum chamber where they were cooled to ≈ 100 K and exposed to a H2O atmosphere at 1 × 10−8 mbar. XPS measurements were performed before and after the exposure to H2O, in-situ and at cryogenic temperatures. The chemical composition of CeO2 did not change significantly during the experiment. Additionally, XPS revealed that little to no ice formed on the surface of CeO2 after the H2O exposure at ≈ 100 K. In contrast, ice was observed all over the sample holder on which the CeO2 was mounted. These findings suggest CeO2 is a promising candidate for future anti-icing coatings and that XPS is a useful technique to investigate the anti-icing properties of surfaces.

• Røst, Håkon; Mazzola, Federico; Bakkelund, Johannes; Åsland, Anna Cecilie; Hu, Jinbang & Cooil, Simon Phillip [Vis alle 8 forfattere av denne artikkelen] (2024). Disentangling electron-boson interactions on the surface of a familiar ferromagnet. Physical review B (PRB). ISSN 2469-9950. 109, s. 1–9. doi: 10.1103/PhysRevB.109.035137. Fulltekst i vitenarkiv Vis sammendrag

  We report energy renormalizations from electron-phonon and electron-magnon interactions in spin minority surface resonances on Ni(111). The different interactions are identified, disentangled, and quantified from the characteristic signatures they provide to the complex self-energy and the largely different binding energies at which they occur. The observed electron-magnon interactions exhibit a strong dependence on momentum and the electron energy band position in the bulk Brillouin zone. In contrast, electron-phonon interactions observed from the same bands appear to be relatively momentum and symmetry independent. Additionally, a moderately strong (λ>0.5) electron-phonon interaction is distinguished from a near-parabolic spin majority band not crossing the Fermi level.

• Mamedov, Damir; Åsland, Anna Cecilie; Cooil, Simon Phillip; Røst, Håkon; Bakkelund, Johannes & Allaniyazov, Atabek [Vis alle 8 forfattere av denne artikkelen] (2023). Enhanced hydrophobicity of CeO<inf>2</inf> thin films: Role of the morphology, adsorbed species and crystallography. Materials Today Communications. 35. doi: 10.1016/j.mtcomm.2023.106323. Fulltekst i vitenarkiv Vis sammendrag

  In order to guarantee the long-term efficiency of hydrophobic materials in real-world situations, it is necessary that their surfaces are highly resistant to scratching, fouling and misting. Furthermore, for the specific applications, e.g. in photovoltaic systems, the water-repelling material must necessarily have a large bandage, such that it does not absorb light in the spectral range which is utilized by the underlying photovoltaic cell. One especially promising candidate for this and many other technologically important applications is cerium dioxide (CeO2, ceria). In the current study, we propose the production framework for the manufacturing of CeO2-based thin films with tunable wetting behavior. For obtaining the coatings with various hydrophobicity, ceria is deposited on the substrates with different roughness via reactive magnetron sputtering, with consequent treatment of the films in vapor of different hydrocarbons. By systematic study using the XRD, SEM, XPS and water contact angle (WCA) instruments, we found that surface texturization, different plains at the surface of the films as well as the adsorbed organic molecules all strongly influence on wettability of the CeO2 thin films. In addition, comparison of WCAs for ceria and silicon oxide SiOx is performed. The higher wettability for the former points out the essential role of the surface material despite presence of hydrocarbons. It is demonstrated that by purposeful controlling for all the parameters – surface texturization, the top material and its crystallography, and adsorbed organic molecules – one can reach superhydrophobic state of the surface.

• Røst, Håkon; Cooil, Simon Phillip; Åsland, Anna Cecilie; Hu, Jinbang; Ali, Ayaz & Taniguchi, Takashi [Vis alle 12 forfattere av denne artikkelen] (2023). Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride. Nano Letters. ISSN 1530-6984. 23(16), s. 7539–7545. doi: 10.1021/acs.nanolett.3c02086. Fulltekst i vitenarkiv Vis sammendrag

  Understanding the collective behavior of the quasiparticles in solid-state systems underpins the field of non-volatile electronics, including the opportunity to control many-body effects for well-desired physical phenomena and their applications. Hexagonal boron nitride (hBN) is a wide energy bandgap semiconductor, showing immense potential as a platform for low-dimensional device heterostructures. It is an inert dielectric used for gated devices, having a negligible orbital hybridization when placed in contact with other systems. Despite its inertness, we discover a large electron mass enhancement in few-layer hBN affecting the lifetime of the pi-band states. We show that the renormalization is phonon-mediated and consistent with both single- and multiple-phonon scattering events. Our findings thus unveil a so-far unknown many-body state in a wide-bandgap insulator, having important implications for devices using hBN as one of their building blocks.

• Åsland, Anna Cecilie; Bakkelund, Johannes; Thingstad, Even; Røst, Håkon; Cooil, Simon Phillip & Hu, Jinbang [Vis alle 11 forfattere av denne artikkelen] (2023). One-dimensional spin-polarized surface states: A comparison of Bi(112) with other vicinal bismuth surfaces. Physical review B (PRB). ISSN 2469-9950. 108(20). doi: 10.1103/PhysRevB.108.205403. Fulltekst i vitenarkiv Vis sammendrag

  Vicinal surfaces of bismuth are unique test beds for investigating one-dimensional (1D) spin-polarized surface states that may one day be used in spintronic devices. In this paper, such states have been observed for the (112) surface when measured using angle- and spin-resolved photoemission spectroscopy, and also when calculated using a tight-binding model and with density functional theory. The surface states appear as elongated Dirac-cones which are 1D and almost dispersionless in the ky direction, but disperse with energy in the orthogonal kx direction to form two ×-like features centered at the ky line through Γ. Unlike many materials considered for spintronic applications, their 1D nature suggests that conductivity and spin-transport properties are highly dependent on direction. The spin polarization of the surface states is mainly in plane and parallel to the 1D states, but there are signs of a tilted out-of-plane spin-vector component for one of the features. The Bi(112) surface states resemble those found for other vicinal surfaces of bismuth, strongly indicating that their existence and general properties are robust properties of vicinal bismuth surfaces. Furthermore, differences in the details of the states, particularly related to their spin polarization, suggest that the electronic band structure may be engineered simply by precise cutting and polishing of the crystal.

• Astley, Simon; Hu, Di; Hazeldine, Kerry; Ash, Johnathan; Cross, Rachel E. & Cooil, Simon Phillip [Vis alle 16 forfattere av denne artikkelen] (2022). Identifying chemical and physical changes in wide-gap semiconductors using real-time and near ambient-pressure XPS. Faraday discussions. ISSN 1359-6640. 236, s. 191–204. doi: 10.1039/d1fd00119a. Fulltekst i vitenarkiv Vis sammendrag

  Photoelectron spectroscopy is a powerful characterisation tool for semiconductor surfaces and interfaces, providing in principle a correlation between the electronic band structure and surface chemistry along with quantitative parameters such as the electron affinity, interface potential, band bending and band offsets. However, measurements are often limited to ultrahigh vacuum and only the top few atomic layers are probed. The technique is seldom applied as an in situ probe of surface processing; information is usually provided before and after processing in a separate environment, leading to a reduction in reproducibility. Advances in instrumentation, in particular electron detection has enabled these limitations to be addressed, for example allowing measurement at near-ambient pressures and the in situ, real-time monitoring of surface processing and interface formation. A further limitation is the influence of the measurement method through irreversible chemical effects such as radiation damage during X-ray exposure and reversible physical effects such as the charging of low conductivity materials. For wide-gap semiconductors such as oxides and carbon-based materials, these effects can be compounded and severe. Here we show how real-time and near-ambient pressure photoelectron spectroscopy can be applied to identify and quantify these effects, using a gold alloy, gallium oxide and semiconducting diamond as examples. A small binding energy change due to thermal expansion is followed in real-time for the alloy while the two semiconductors show larger temperature-induced changes in binding energy that, although superficially similar, are identified as having different and multiple origins, related to surface oxygen bonding, surface band-bending and a room-temperature surface photovoltage. The latter affects the p-type diamond at temperatures up to 400 °C when exposed to X-ray, UV and synchrotron radiation and under UHV and 1 mbar of O2. Real-time monitoring and near-ambient pressure measurement with different excitation sources has been used to identify the mechanisms behind the observed changes in spectral parameters that are different for each of the three materials. Corrected binding energy values aid the completion of the energy band diagrams for these wide-gap semiconductors and provide protocols for surface processing to engineer key surface and interface parameters.

• Reed, B.P.; Bathen, Marianne Etzelmüller; Ash, J.W.R.; Meara, C.J.; Zakharov, A.A. & Goss, J.P. [Vis alle 9 forfattere av denne artikkelen] (2022). Diamond (111) surface reconstruction and epitaxial graphene interface. Physical review B (PRB). ISSN 2469-9950. 105(20). doi: 10.1103/PhysRevB.105.205304. Fulltekst i vitenarkiv
• Røst, Håkon Ivarssønn; Reed, Benjamen P.; Strand, Frode Sneve; Durk, Joseph A.; Evans, D. Andrew & Grubišić-Čabo, Antonija [Vis alle 18 forfattere av denne artikkelen] (2021). A Simplified Method for Patterning Graphene on Dielectric Layers. ACS Applied Materials & Interfaces. ISSN 1944-8244. 13(31), s. 37510–37516. doi: 10.1021/acsami.1c09987. Fulltekst i vitenarkiv Vis sammendrag

  The large-scale formation of patterned, quasi-freestanding graphene structures supported on a dielectric has so far been limited by the need to transfer the graphene onto a suitable substrate and contamination from the associated processing steps. We report μm scale, few-layer graphene structures formed at moderate temperatures (600–700 °C) and supported directly on an interfacial dielectric formed by oxidizing Si layers at the graphene/substrate interface. We show that the thickness of this underlying dielectric support can be tailored further by an additional Si intercalation of the graphene prior to oxidation. This produces quasi-freestanding, patterned graphene on dielectric SiO2 with a tunable thickness on demand, thus facilitating a new pathway to integrated graphene microelectronics.

• Michels, Leander; Richter, Annika; Chellappan, Rajesh Kumar; Røst, Håkon Ivarssønn; Behsen, Alenka Djarmila & Wells, Kristin Høydalsvik [Vis alle 13 forfattere av denne artikkelen] (2021). Electronic and structural properties of the natural dyes curcumin, bixin and indigo. RSC Advances. 11(23), s. 14169–14177. doi: 10.1039/d0ra08474c. Fulltekst i vitenarkiv Vis sammendrag

  An optical, electronic and structural characterisation of three natural dyes potentially interesting for application in organic solar cells, curcumin (C21H20O6), bixin (C25H30O4) and indigo (C16H10N2O2), was performed. X-Ray Diffraction (XRD) measurements, showed that curcumin has a higher degree of crystallinity compared to bixin and indigo. The results from the Pawley unit cell refinements for all dyes are reported. Optical absorption spectra measured by UV-Visible Spectroscopy (UV-Vis) on thermally evaporated films revealed that bixin undergoes chemical degradation upon evaporation, while curcumin and indigo appear to remain unaffected by this process. Combined Ultraviolet Photoemission Spectroscopy (UPS) and Inverse Photoemission Spectroscopy (IPES) spectra measured on the dyes revealed that all of them are hole-conducting materials and allowed for the determination of their electronic bandgaps, and Fermi level position within the gap. UV Photo-Emission Electron Microscopy (PEEM) revealed the workfunction of the dye materials and indicated that indigo has a negative electron affinity. PEEM was also used to study degradation by UV irradiation and showed that they are quite robust to UV exposure.

• Røst, Håkon Ivarssønn; Chellappan, Rajesh Kumar; Strand, Frode Sneve; Grubišić-Čabo, Antonija; Reed, Benjamen P. & Prieto, Mauricio J. [Vis alle 16 forfattere av denne artikkelen] (2021). Low-Temperature Growth of Graphene on a Semiconductor. Journal of Physical Chemistry C. ISSN 1932-7447. 125(7), s. 4243–4252. doi: 10.1021/acs.jpcc.0c10870. Fulltekst i vitenarkiv Vis sammendrag

  The industrial realization of graphene has so far been limited by challenges related to the quality, reproducibility, and high process temperatures required to manufacture graphene on suitable substrates. We demonstrate that epitaxial graphene can be grown on transition-metal-treated 6H-SiC(0001) surfaces, with an onset of graphitization starting around 450–500 °C. From the chemical reaction between SiC and thin films of Fe or Ru, sp3 carbon is liberated from the SiC crystal and converted to sp2 carbon at the surface. The quality of the graphene is demonstrated by using angle-resolved photoemission spectroscopy and low-energy electron diffraction. Furthermore, the orientation and placement of the graphene layers relative to the SiC substrate are verified by using angle-resolved absorption spectroscopy and energy-dependent photoelectron spectroscopy, respectively. With subsequent thermal treatments to higher temperatures, a steerable diffusion of the metal layers into the bulk SiC is achieved. The result is graphene supported on magnetic silicide or optionally, directly on semiconductor, at temperatures ideal for further large-scale processing into graphene-based device structures.

• Pakpour-Tabrizi, Alex; Schenk, Alex Kevin; Holt, Ann Julie; Mahatha, S.K.; Arnold, Fabian & Bianchi, Marco [Vis alle 14 forfattere av denne artikkelen] (2020). The occupied electronic structure of ultrathin boron doped diamond. Nanoscale Advances. 2(3), s. 1358–1364. doi: 10.1039/C9NA00593E. Fulltekst i vitenarkiv Vis sammendrag

  Using angle-resolved photoelectron spectroscopy, we compare the electronic band structure of an ultrathin (1.8 nm) δ-layer of boron-doped diamond with a bulk-like boron doped diamond film (3 μm). Surprisingly, the measurements indicate that except for a small change in the effective mass, there is no significant difference between the electronic structure of these samples, irrespective of their physical dimensionality, except for a small modification of the effective mass. While this suggests that, at the current time, it is not possible to fabricate boron-doped diamond structures with quantum properties, it also means that nanoscale boron doped diamond structures can be fabricated which retain the classical electronic properties of bulk-doped diamond, without a need to consider the influence of quantum confinement.

• Holt, Ann Julie; Mahatha, Sanjoy K.; Stan, Raluca-Maria; Strand, Frode Sneve; Nyborg, Thomas & Curcio, Davide [Vis alle 12 forfattere av denne artikkelen] (2020). Observation and origin of the [delta] manifold in Si:P [delta] layers. Physical review B (PRB). ISSN 2469-9950. 101(12). doi: 10.1103/PhysRevB.101.121402. Fulltekst i vitenarkiv
• Schenk, Alex Kevin; Pakpour-Tabrizi, Alex; Holt, Ann Julie; mahatha, s.k.; Arnold, Fabian & Bianchi, Marco [Vis alle 12 forfattere av denne artikkelen] (2019). The occupied electronic structure of ultrathin boron doped diamond. arXiv.org. ISSN 2331-8422. 1907, s. 00673–00673. Fulltekst i vitenarkiv
• Bahramy, Mohammed Saeed; Clark, Oliver J.; Yang, Bohm Jung; Feng, Jiagui; Bawden, Lewis & Riley, Jonathon M. [Vis alle 26 forfattere av denne artikkelen] (2018). Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides. Nature Materials. ISSN 1476-1122. 17(1), s. 21–27. doi: 10.1038/NMAT5031. Fulltekst i vitenarkiv
• Risinggård, Helene Kjær; Cooil, Simon Phillip; Mazzola, Federico; Hu, Di; Kjærvik, Marit & Østli, Elise Ramleth [Vis alle 12 forfattere av denne artikkelen] (2018). Degradation of the chemotherapy drug 5-fluorouracil on medical-grade silver surfaces. Applied Surface Science. ISSN 0169-4332. 435, s. 1213–1219. doi: 10.1016/j.apsusc.2017.11.221. Fulltekst i vitenarkiv
• Kjeldby, Snorre Braathen; Evenstad, Otto Magnus; Cooil, Simon Phillip & Wells, Justin (2017). Probing dimensionality using a simplified 4-probe method. Journal of Physics: Condensed Matter. ISSN 0953-8984. 29(39). doi: 10.1088/1361-648X/aa8296. Fulltekst i vitenarkiv
• Jorge, Marina; Polyakov, Stanislav; Cooil, Simon Phillip; Schenk, Alex Kevin; Edmonds, Mark & Thomsen, Lars [Vis alle 8 forfattere av denne artikkelen] (2017). Robust p-type doping of copper oxide using nitrogen implantation. Materials Research Express. 4(7). doi: 10.1088/2053-1591/aa7613. Fulltekst i vitenarkiv Vis sammendrag

  We demonstrate robust p-type doping of Cu2O using low/medium energy ion implantation. Samples are made by controlled oxidation of annealed Cu metal foils, which results in Cu2O with levels of doping close to intrinsic. Samples are then implanted with nitrogen ions using a kinetic energy in the few keV range. Using this method, we are able to produce very high levels of doping, as evidenced by a 350 meV shift in the Fermi level towards the VB maximum. The robustness of the nitrogen implanted samples are tested by exposing them to atmospheric contaminants, and elevated temperatures. The samples are found to survive an increase in temperature of many hundreds of degrees. The robustness of the samples, combined with the fact that the materials used are safe, abundant and non-toxic and that the methods used for the growth of Cu2O and N+ implantation are simple and cheap to implement industrially, underlines the potential of Cu2O:N for affordable intermediate band photovoltaics.

• Jorge, Marina; Cooil, Simon Phillip; Edmonds, Mark; Thomsen, Lars; Nematollahi, Mohammadreza & Mazzola, Federico [Vis alle 7 forfattere av denne artikkelen] (2017). Accelerated ageing of molybdenum oxide. Materials Research Express. 4(11). doi: 10.1088/2053-1591/aa9287. Fulltekst i vitenarkiv
• Cooil, Simon Phillip; Mazzola, Federico; Klemm, Hagen W; Peschel, Gina; Niu, Yuran R & Zakharov, Alexei A [Vis alle 11 forfattere av denne artikkelen] (2017). In Situ Patterning of Ultrasharp Dopant Profiles in Silicon. ACS Nano. ISSN 1936-0851. 11(2), s. 1683–1688. doi: 10.1021/acsnano.6b07359. Fulltekst i vitenarkiv
• Vinje, Jakob; Falck, Merete; Mazzola, Federico; Cooil, Simon Phillip; Koch, Henrik & Høyvik, Ida-Marie [Vis alle 7 forfattere av denne artikkelen] (2017). Tautomerization of thymine using ultraviolet light. Langmuir. ISSN 0743-7463. 33(38), s. 9666–9672. doi: 10.1021/acs.langmuir.7b02473. Fulltekst i vitenarkiv
• Bawden, L; Cooil, Simon Phillip; Mazzola, Federico; Riley, JM; Collins-Mcintyre, LJ & Sunko, V [Vis alle 16 forfattere av denne artikkelen] (2016). Spin-valley locking in the normal state of a transition-metal dichalcogenide superconductor. Nature Communications. 7. doi: 10.1038/ncomms11711. Fulltekst i vitenarkiv Vis sammendrag

  Metallic transition-metal dichalcogenides (TMDCs) are benchmark systems for studying and controlling intertwined electronic orders in solids, with superconductivity developing from a charge-density wave state. The interplay between such phases is thought to play a critical role in the unconventional superconductivity of cuprates, Fe-based and heavy-fermion systems, yet even for the more moderately-correlated TMDCs, their nature and origins have proved controversial. Here, we study a prototypical example, 2H-NbSe2, by spin- and angle-resolved photoemission and first-principles theory. We find that the normal state, from which its hallmark collective phases emerge, is characterized by quasiparticles whose spin is locked to their valley pseudospin. This results from a combination of strong spin–orbit interactions and local inversion symmetry breaking, while interlayer coupling further drives a rich three-dimensional momentum dependence of the underlying Fermi-surface spin texture. These findings necessitate a re-investigation of the nature of charge order and superconducting pairing in NbSe2 and related TMDCs.

• Cooil, Simon Phillip; Mørtsell, Eva Anne; Mazzola, Federico; Jorge, Marina; Wenner, Sigurd & Edmonds, M T [Vis alle 15 forfattere av denne artikkelen] (2016). Thermal migration of alloying agents in aluminium. Materials Research Express. 3(11). doi: 10.1088/2053-1591/3/11/116501. Fulltekst i vitenarkiv Vis sammendrag

  The in situ thermal migration of alloying agents in an Al–Mg–Si–Li alloy is studied using surface sensitive photo-electron and electron diffraction/imaging techniques. Starting with the preparation of an almost oxide free surface (oxide thickness = 0.1 nm), the relative abundance of alloying agents (Mg, Li and Si) at the surface are recorded at various stages of thermal annealing, from room temperature to melting (which is observed at 550 ◦C). Prior to annealing, the surface abundances are below the detection limit Lt1%, in agreement with their bulk concentrations of 0.423% Si, 0.322% Mg and 0.101% Li (atomic %). At elevated temperatures, all three alloying agents appear at drastically increased concentrations (13.3% Si, 19.7% Mg and 45.3% Li), but decrease again with further elevation of the annealing temperature or after melting. The temperature at which the migration occurs is species dependent, with Li migration occurring at significantly higher temperatures than Si and Mg. The mechanism of migration also appears to be species dependent with Li migration occurring all over the surface but Mg migration being restricted to grain boundaries.

• Mazzola, Federico; Nematollahi, Mohammadreza; Li, Zheshen; Cooil, Simon, Phillip; Yang, Xiaodong & Reenaas, Turid Worren [Vis alle 7 forfattere av denne artikkelen] (2015). Resonant photoemission spectroscopy for intermediate band materials. Applied Physics Letters. ISSN 0003-6951. 107:192102(19). doi: 10.1063/1.4935536. Fulltekst i vitenarkiv Vis sammendrag

  Resonant photoemission spectroscopy is used to study the intermediate-band material Cr dopedZnS. Using resonant photoemission, we show that the intermediate-band can be characterized, revealing the filling and specific orbital character of the states contributing to the resonant photoemission signal. We demonstrate that resonant photoemission spectroscopy is a powerful approach for understanding the origin of intermediate bands in dopedZnS. The methodology can be widely extended to a large variety of materials, providing useful information towards engineering of high efficiency intermediate band solar cells and of other optoelectronic devices.

• Cooil, Simon, Phillip; Wells, Justin; Hu, Di; Niu, Yuran; Zakharov, Alexei & Bianchi, Marco [Vis alle 7 forfattere av denne artikkelen] (2015). Controlling the growth of epitaxial graphene on metalized diamond (111) surface. Applied Physics Letters. ISSN 0003-6951. 107:181603(18). doi: 10.1063/1.4935073. Fulltekst i vitenarkiv Vis sammendrag

  The 2-dimensional transformation of the diamond (111) surface to graphene has been demonstrated using ultrathin Fe films that catalytically reduce the reaction temperature needed for the conversion of sp3 to sp2 carbon. An epitaxial system is formed, which involves the re-crystallization of carbon at the Fe/vacuum interface and that enables the controlled growth of monolayer and multilayer graphene films. In order to study the initial stages of single and multilayer graphene growth, real time monitoring of the system was preformed within a photoemission and low energy electron microscope. It was found that the initial graphene growth occurred at temperatures as low as 500 °C, whilst increasing the temperature to 560 °C was required to produce multi-layer graphene of high structural quality. Angle resolved photoelectron spectroscopy was used to study the electronic properties of the grown material, where a graphene-like energy momentum dispersion was observed. The Dirac point for the first layer is located at 2.5 eV below the Fermi level, indicating an n-type doping of the graphene due to substrate interactions, while that of the second graphene layer lies close to the Fermi level.

• Mazzola, Federico; Trinh, Thuat; Cooil, Simon, Phillip; Østli, Elise Ramleth; Høydalsvik, Kristin & Skjønsfjell, Eirik Torbjørn Bakken [Vis alle 12 forfattere av denne artikkelen] (2015). Graphene coatings for chemotherapy: avoiding silver-mediated degradation. 2D Materials. 2(2), s. 025004–025004. doi: 10.1088/2053-1583/2/2/025004. Fulltekst i vitenarkiv
• Bianchi, M; Song, F; Cooil, Simon Phillip; Monsen, Åsmund Fløystad; Wahlström, Erik & Miwa, JA [Vis alle 14 forfattere av denne artikkelen] (2015). One-dimensional spin texture of Bi(441): Quantum spin Hall properties without a topological insulator. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 91(16). doi: 10.1103/PhysRevB.91.165307. Fulltekst i vitenarkiv
• Beckwith, Kai Sandvold; Cooil, Simon Phillip; Wells, Justin & Sikorski, Pawel (2015). Tunable high aspect ratio polymer nanostructures for cell interfaces. Nanoscale. ISSN 2040-3364. 7(18), s. 8438–8450. doi: 10.1039/c5nr00674k. Fulltekst i vitenarkiv Vis sammendrag

  Nanoscale topographies and chemical patterns can be used as synthetic cell interfaces with a range of applications including study and control of cellular processes. Herein, we describe the fabrication of high aspect ratio nanostructures using electron beam lithography in the epoxy-based polymer SU-8. We show how nanostructure geometry, position and fluorescent properties can be tuned, allowing flexible device design. Further, thiol-epoxide reactions were developed to give effective and specific modification of SU-8 surface chemistry. SU-8 nanostructures were made directly on glass cover slips, enabling the use of high resolution optical techniques such as live-cell confocal, total internal reflection and 3D structured illumination microscopy to investigate cell interactions with the nanostructures. Details of cell adherence and spreading, plasma membrane conformation and actin organization in response to high aspect ratio nanopillars and nanolines were investigated. The versatile structural and chemical properties combined with high resolution cell imaging capabilities of this system are an important step towards better understanding and controlling cell interactions with nanomaterials.

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• Schenk, Richard Justin; Skarpeid, Alv; Røst, Håkon; Yadav, Rohit; Cooil, Simon Phillip & Wells, Justin William (2026). Modifying the Electronic Structure of Nickel with Antimony Surface Alloys. Fulltekst i vitenarkiv
• Kjeldby, Snorre Braathen; Olsen, Vegard Skiftestad; Frodason, Ymir Kalmann; Zacharaki, Eirini; Cooil, Simon Phillip & Vines, Lasse [Vis alle 12 forfattere av denne artikkelen] (2025). Thin film top cell absorbers for multijunction solar cells. Fulltekst i vitenarkiv
• Stalsberg, Marte Pedersen; Schenk, Richard Justin; Roberts, Daniel; Rørheim, Adrian Næraa; Moen-Duran, Oliver & Wells, Justin William [Vis alle 7 forfattere av denne artikkelen] (2024). Towards a p-n heterojunction of Ga2O3 and diamond. Fulltekst i vitenarkiv
• Stalsberg, Marte Pedersen; Strand, Frode Sneve; Cooil, Simon Phillip; Campbell, Quinn T.; Flounders, John J. & Røst, Håkon Ivarssønn [Vis alle 10 forfattere av denne artikkelen] (2024). A 2D electron gas by shallow Sb doping in Si for use in Quantum Devices. Fulltekst i vitenarkiv
• Stalsberg, Marte Pedersen; Wells, Justin William & Cooil, Simon Phillip (2024). Towards a p-n Heterojunction from Ga2O3 and Diamond. Fulltekst i vitenarkiv
• Åsland, Anna Cecilie; Cooil, Simon Phillip; Mamedov, Damir; Røst, Håkon Ivarssønn; Bakkelund, Johannes & Karazhanov, Smagul [Vis alle 7 forfattere av denne artikkelen] (2024). Initial Stages of Water Absorption on CeO2 Surfaces at Very Low Temperatures for Understanding Anti-Icing Coatings. Fulltekst i vitenarkiv
• Jensen, Ingvild Julie Thue; Thøgersen, Annett; Cooil, Simon Phillip; Wells, Justin William; Prytz, Øystein & Wenckstern, Holger Von (2023). Bandgap and band offset engineering in κ-Ga2O3-based thin films (Invited talk)). Fulltekst i vitenarkiv
• Stalsberg, Marte Pedersen; Strand, Frode Sneve; Cooil, Simon Phillip; Campbell, Quinn T.; Flounders, John J. & Røst, Håkon Ivarssønn [Vis alle 10 forfattere av denne artikkelen] (2023). Atomically Sharp and High-Density Sb Doping in Si for use in Quantum Devices. Fulltekst i vitenarkiv
• Olsen, Vegard Skiftestad; Øversjøen, Vetle; Frodason, Ymir Kalmann; Cooil, Simon; Lee, In-Hwan & Vines, Lasse [Vis alle 7 forfattere av denne artikkelen] (2021). Electrical control in ZnSnN2 by tailoring intrinsic and extrinsic defects. Fulltekst i vitenarkiv
• Chellappan, Rajesh Kumar; Cooil, Simon Phillip; Dahl, Oystein & Wells, Justin (2019). Insitu study of graphene patterning on SiC. Fulltekst i vitenarkiv
• Schenk, Alex Kevin; Pakpour-Tabrizi, Alex; Mazzola, Federico; Holt, Ann Julie; Nyborg, Thomas & Cooil, Simon Phillip [Vis alle 13 forfattere av denne artikkelen] (2018). Using ARPES as a tool for exploring quantisation in delta-doped silicon and diamond. Fulltekst i vitenarkiv
• Chellappan, Rajesh Kumar; Cooil, Simon Phillip; Dahl, Oystein & Wells, Justin (2018). Transition metal mediated growth of epitaxial graphene on SiC and intercalation of SiOx for radiation sensing application. Fulltekst i vitenarkiv
• Vinje, Jakob; Beckwith, Kai Sandvold; Cooil, Simon Phillip; Wells, Justin & Sikorski, Pawel (2017). Nano-structuring and controlled surface chemistry for cell-studies and biomedical applications. Fulltekst i vitenarkiv
• Vinje, Jakob; Beckwith, Kai Sandvold; Cooil, Simon Phillip; Wells, Justin & Sikorski, Pawel (2017). Nano-structured surfaces and controlled surface chemistry for cell studies. Fulltekst i vitenarkiv
• Michels, Leander; Patil, Nilesh; Cooil, Simon, Phillip; Coucheron, David Andre; Fokine, Michael & Schleputz, Christian [Vis alle 9 forfattere av denne artikkelen] (2016). SiGe in confined fiber geometry. Fulltekst i vitenarkiv

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