Justin William Wells

Professor - Semiconductor physics

Norwegian version of this page

Email j.w.wells@fys.uio.no

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Visiting address Gaustadalléen 23a Kristen Nygaards hus 0373 Oslo

Postal address Postboks 1048 Blindern 0316 Oslo

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Webpage

My group webpage can be found here:
https://sites.google.com/site/quantumwells/home

Academic interests

My current activities revolve around a common theme of condensed matter and semiconductor physics. The majority of the activities involve experimental surface physics techniques (photoemission spectroscopies: XPS, UPS, ARPES, spin-ARPES and PEEM, and related techniques AES, LEED, inverse photoemission and 4-probe transport). The majority of the activities are experimental, but analytical and computational methods are also used as required. Within the envelopes of “condensed matter physics” and “surface science”, the research activities are very broad. Recent and ongoing topics include: Quantum engineering in silicon; spin physics in topological insulators and quasi-2D materials; quasiparticle (electron-phonon and electron-magnon) formation in surfaces and interfaces; development of 4-probe methods; organic self-assembly of quantum wells; and organic and oxide semiconductors for photovoltaic applications. In 2018 I co-founded Center of Excellence (SFF) QuSpin at NTNU, where I have had primary responsibility for the experimental side of the activities.

Aside from my primary interests, I have small “hobby” projects which include; chemistry of COVID testing, chemotherapy and skin-cancer chemistry; graphene gated photo-sensors and commercial metal alloying, as well as an interest in restoring and developing lab instrumentation.

Many of my activities involve national and/or international collaboration, with important collaborations at NTNU, as well as in Universities in Bergen, Aarhus, Copenhagen, Lund, Gothenburg, Berlin, Basel, Zürich, London, Aberystwyth, Bristol, San Sebastian, Shanghai, Melbourne, Sydney, Brasilia, and several other places. In addition to University collaborations, there are important collaborations with a number of research institutes and companies (Sintef, Elkem, Newtec A/S and Focus GmbH).

Positions held

2020 - Professor, Department of Physics, University of Oslo, Norway.
2017 -2021: Professor, Center for Quantum Spintronics & Department of Physics, NTNU, Trondheim, Norway.
2012 - 2017: Associate Professor, Department of Physics, NTNU, Trondheim, Norway.
2011 - 2012: Post-doctoral researcher at Lund University and MAXLab, Lund, Sweden.
2008 - 2011: Post-doctoral researcher, Norwegian University of Science and Technology (NTNU), Trondheim, Norway, Member of the group of Erik Wahlström.
2006 - 2008: Post-doctoral researcher at Aarhus University, Aarhus, Denmark, Member of the group of Professor Philip Hofmann.
2003 - 2006: Ph.D. Fellowship, Aarhus University, Aarhus, Denmark Supervisor: Professor Philip Hofmann.
2001-2003: Research Assistant at Trinity College, Dublin, Ireland.

Tags: SMN, LENS, Semiconductor physics

Tuniz, Manuel; Consiglio, Armando; Puntel, Denny; Bigi, Chiara; Enzner, Stefan & Pokharel, Ganesh [Show all 25 contributors for this article] (2023). Dynamics and resilience of the unconventional charge density wave in ScV6Sn6 bilayer kagome metal. Communications Materials. ISSN 2662-4443. 4(1), p. 1–8. doi: 10.1038/s43246-023-00430-y. Show summary
Long-range electronic ordering descending from a metallic parent state constitutes a rich playground to study the interplay of structural and electronic degrees of freedom. In this framework, kagome metals are in the most interesting regime where both phonon and electronically mediated couplings are significant. Several of these systems undergo a charge density wave transition. However, to date, the origin and the main driving force behind this charge order is elusive. Here, we use the kagome metal ScV6Sn6 as a platform to investigate this problem, since it features both a kagome-derived nested Fermi surface and van-Hove singularities near the Fermi level, and a charge-ordered phase that strongly affects its physical properties. By combining time-resolved reflectivity, first principles calculations and photo-emission experiments, we identify the structural degrees of freedom to play a fundamental role in the stabilization of charge order, indicating that ScV6Sn6 features an instance of charge order predominantly originating from phonons.
Åsland, Anna Cecilie; Bakkelund, Johannes; Thingstad, Even; Røst, Håkon; Cooil, Simon Phillip & Hu, Jinbang [Show all 11 contributors for this article] (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. Full text in Research Archive Show summary
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.
Røst, Håkon; Cooil, Simon Phillip; Åsland, Anna Cecilie; Hu, Jinbang; Ali, Ayaz & Taniguchi, Takashi [Show all 12 contributors for this article] (2023). Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride. Nano Letters. ISSN 1530-6984. 23(16), p. 7539–7545. doi: 10.1021/acs.nanolett.3c02086. Full text in Research Archive Show summary
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.
Mamedov, Damir; Åsland, Anna Cecilie; Cooil, Simon Phillip; Røst, Håkon; Bakkelund, Johannes & Allaniyazov, Atabek [Show all 8 contributors for this article] (2023). Enhanced hydrophobicity of CeO<inf>2</inf> thin films: Role of the morphology, adsorbed species and crystallography. Materials Today Communications. ISSN 2352-4928. 35. doi: 10.1016/j.mtcomm.2023.106323. Full text in Research Archive
Røst, Håkon; Tosi, Ezequiel; Strand, Frode Sneve; Åsland, Anna Cecilie; Lacovig, Paolo & Lizzit, Silvano [Show all 7 contributors for this article] (2023). Probing the Atomic Arrangement of Subsurface Dopants in a Silicon Quantum Device Platform. ACS Applied Materials & Interfaces. ISSN 1944-8244. 15(18), p. 22637–22643. doi: 10.1021/acsami.2c23011. Full text in Research Archive
Reed, B.P.; Bathen, Marianne Etzelmüller; Ash, J.W.R.; Meara, C.J.; Zakharov, A.A. & Goss, J.P. [Show all 9 contributors for this article] (2022). Diamond (111) surface reconstruction and epitaxial graphene interface. Physical review B (PRB). ISSN 2469-9950. 105(20). doi: 10.1103/PhysRevB.105.205304.
Mæland, Kristian; Røst, Håkon Ivarssønn; Wells, Justin William & Sudbø, Asle (2021). Electron-magnon coupling and quasiparticle lifetimes on the surface of a topological insulator. Physical review B (PRB). ISSN 2469-9950. 104(12). doi: 10.1103/PhysRevB.104.125125. Full text in Research Archive Show summary
The fermionic self-energy on the surface of a topological insulator proximity coupled to ferro- and antiferromagnetic insulators is studied. An enhanced electron-magnon coupling is achieved by allowing the electrons on the surface of the topological insulator to have a different exchange coupling to the two sublattices of the antiferromagnet. Such a system is therefore seen as superior to a ferromagnetic interface for the realization of magnon-mediated superconductivity. The increased electron-magnon-coupling simultaneously increases the self-energy effects. In this paper we show how the inverse quasiparticle lifetime and energy renormalization on the surface of the topological insulator can be kept low close to the Fermi level by using a magnetic insulator with a sufficient easy-axis anisotropy. We find that the antiferromagnetic case is most interesting from both a theoretical and an experimental standpoint due to the increased electron-magnon coupling, combined with a reduced need for easy-axis anisotropy compared to the ferromagnetic case. We also consider a set of material and instrumental parameters where these self-energies should be measurable in angle-resolved photoemission spectroscopy experiments, paving the way for a measurement of the interfacial exchange coupling strength.
Røst, Håkon Ivarssønn; Reed, Benjamen P.; Strand, Frode Sneve; Durk, Joseph A.; Evans, D. Andrew & Grubišić-Čabo, Antonija [Show all 18 contributors for this article] (2021). A Simplified Method for Patterning Graphene on Dielectric Layers. ACS Applied Materials & Interfaces. ISSN 1944-8244. 13(31), p. 37510–37516. doi: 10.1021/acsami.1c09987. Full text in Research Archive
Michels, Leander; Richter, Annika; Chellappan, Rajesh Kumar; Røst, Håkon Ivarssønn; Behsen, Alenka Djarmila & Wells, Kristin Høydalsvik [Show all 13 contributors for this article] (2021). Electronic and structural properties of the natural dyes curcumin, bixin and indigo. RSC Advances. ISSN 2046-2069. 11(23), p. 14169–14177. doi: 10.1039/d0ra08474c. Full text in Research Archive
Holst, Bodil; Alexandrowicz, Gil; Avidor, Nadav; Benedek, Giorgio; Bracco, Gianangelo & Ernst, Wolfgang E. [Show all 16 contributors for this article] (2021). Material properties particularly suited to be measured with helium scattering: selected examples from 2D materials, van der Waals heterostructures, glassy materials, catalytic substrates, topological insulators and superconducting radio frequency materials. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 23(13), p. 7653–7672. doi: 10.1039/d0cp05833e. Full text in Research Archive
Røst, Håkon Ivarssønn; Chellappan, Rajesh Kumar; Strand, Frode Sneve; Grubišić-Čabo, Antonija; Reed, Benjamen P. & Prieto, Mauricio J. [Show all 16 contributors for this article] (2021). Low-Temperature Growth of Graphene on a Semiconductor. Journal of Physical Chemistry C. ISSN 1932-7447. 125(7), p. 4243–4252. doi: 10.1021/acs.jpcc.0c10870. Full text in Research Archive
Hu, Jinbang; Strand, Frode Sneve; Chellappan, Rajesh Kumar; Zhang, Zhengde; Shen, Kongchao & Hu, JinPing [Show all 13 contributors for this article] (2020). Direct Synthesis of Semimetal Phthalocyanines on a Surface with Insights into Interfacial Properties. The Journal of Physical Chemistry Letters. ISSN 1948-7185. 124(15), p. 8247–8256. doi: 10.1021/acs.jpcc.0c00895.
Hu, Jinbang; Hu, JinPing; Zhang, Zhengde; Shen, Kongchao; Liang, Zhaofeng & Zhang, Huan [Show all 12 contributors for this article] (2020). Ullmann coupling of 2,7-dibromopyrene on Au (1 1 1) assisted by surface adatoms. Applied Surface Science. ISSN 0169-4332. 513. doi: 10.1016/j.apsusc.2020.145797.
Mazzola, Federico; Chen, Chin-Yi; Rahman, Rajib; Zhu, Xie-Gang; Polley, Craig & Balasubramanian, Thiagarajan [Show all 10 contributors for this article] (2020). The sub-band structure of atomically sharp dopant profiles in silicon. npj Quantum Materials. ISSN 2397-4648. 5(1).
Holt, Ann Julie; Mahatha, Sanjoy K.; Stan, Raluca-Maria; Strand, Frode Sneve; Nyborg, Thomas & Curcio, Davide [Show all 12 contributors for this article] (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.
Pakpour-Tabrizi, Alex; Schenk, Alex Kevin; Holt, Ann Julie; Mahatha, S.K.; Arnold, Fabian & Bianchi, Marco [Show all 14 contributors for this article] (2020). The occupied electronic structure of ultrathin boron doped diamond. Nanoscale Advances. 2(3), p. 1358–1364. doi: 10.1039/C9NA00593E. Full text in Research Archive
Thingstad, Even; Kamra, Akashdeep; Wells, Justin & Sudbø, Asle (2020). Phonon-mediated superconductivity in doped monolayer materials. Physical review B (PRB). ISSN 2469-9950. 101(21). doi: 10.1103/PhysRevB.101.214513. Full text in Research Archive Show summary
Insight into why superconductivity in pristine and doped monolayer graphene seems strongly suppressed has been central for the recent years' various creative approaches to realize superconductivity in graphene and graphene-like systems. We provide further insight by studying electron-phonon coupling and superconductivity in doped monolayer graphene and hexagonal boron nitride based on intrinsic phonon modes. Solving the graphene gap equation using a detailed model for the effective attraction based on electron tight binding and phonon force constant models, the various system parameters can be tuned at will. Consistent with results in the literature, we find slight gap modulations along the Fermi surface, and the high-energy phonon modes are shown to be the most significant for the superconductivity instability. The Coulomb interaction plays a major role in suppressing superconductivity at realistic dopings. Motivated by the direct onset of a large density of states at the Fermi surface for small charge dopings in hexagonal boron nitride, we also calculate the dimensionless electron-phonon coupling strength there, but the comparatively large density of states cannot immediately be capitalized on, and the charge doping necessary to obtain significant electron-phonon coupling is similar to the value in graphene.
Hu, Jinbang; Shen, Kongchao; Hu, Jinping; Sun, Haoliang; Tian, Qiwei & Zhaofeng, * [Show all 11 contributors for this article] (2019). Structural Transformation of 2,7-Dibromopyrene on Au(111) Mediated by Halogen-Bonding Motifs. ChemPhysChem. ISSN 1439-4235. 20(18), p. 2376–2381. doi: 10.1002/cphc.201900259.
Mazzola, Federico; Chen, Chin-Yi; Rahman, Rajib; Zhu, Xie-Gang; Polley, Craig & Balasubramanian, Thiagarajan [Show all 10 contributors for this article] (2019). The Sub-band Structure of Atomically Sharp Dopant Profiles in Silicon. arXiv.org. ISSN 2331-8422. 1904(10929). doi: 10.1038/s41535-020-0237-1.
Hofmann, Philip; Ugeda, Miguel; Tamtogl, Anton; Ruckhofer, Adrian; Ernst, Wolfgang E & Benedek, Giorgio [Show all 13 contributors for this article] (2019). Strong-coupling charge density wave in a one-dimensional topological metal. Physical review B (PRB). ISSN 2469-9950. 99(3). doi: 10.1103/PhysRevB.99.035438.
Schenk, Alex Kevin; Pakpour-Tabrizi, Alex; Holt, Ann Julie; mahatha, s.k.; Arnold, Fabian & Bianchi, Marco [Show all 12 contributors for this article] (2019). The occupied electronic structure of ultrathin boron doped diamond. arXiv.org. ISSN 2331-8422. 1907.
Shen, Kongchao; Sun, Haoliang; Hu, Jinping; Hu, Jinbang; Liang, Zhaofeng & Li, Haiyang [Show all 14 contributors for this article] (2018). Fabricating Quasi-Free-Standing Graphene on a SiC (0001) Surface by Steerable Intercalation of Iron. Journal of Physical Chemistry C. ISSN 1932-7447. 122(37), p. 21484–21492. doi: 10.1021/acs.jpcc.8b06789.
Bahramy, Mohammed Saeed; Clark, Oliver J.; Yang, Bohm Jung; Feng, Jiagui; Bawden, Lewis & Riley, Jonathon M. [Show all 26 contributors for this article] (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), p. 21–27. doi: 10.1038/NMAT5031.
Hellsing, Bo; Frederiksen, Thomas; Mazzola, Federico; Balasubramanian, Thiagarajan & Wells, Justin (2018). Phonon-induced linewidths of graphene electronic states. Physical review B (PRB). ISSN 2469-9950. 98:205428(20), p. 1–7. doi: 10.1103/PhysRevB.98.205428.
Mazzola, Federico; Wells, Justin; Pakpour-Tabrizi, Alex; Jackman, Richard; Thiagarajan, Balusubramanian & Hofmann, Philip [Show all 7 contributors for this article] (2018). Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors. Physical Review Letters. ISSN 0031-9007. 120(4), p. 046403-1–046403-5. doi: 10.1103/PhysRevLett.120.046403.
Mazzola, Federico; Wells, Justin; Pakpour-Tabrizi, Alex; Jackman, Richard; Thiagarajan, Balusubramanian & Hofmann, Philip [Show all 7 contributors for this article] (2018). Simultaneous conduction and valence band quantisation in ultra-shallow, high density doping profiles in semiconductors. arXiv.org. ISSN 2331-8422.
Risinggård, Helene Kjær; Cooil, Simon Phillip; Mazzola, Federico; Hu, Di; Kjærvik, Marit & Østli, Elise Ramleth [Show all 11 contributors for this article] (2018). Degradation of the chemotherapy drug 5-fluorouracil on medical-grade silver surfaces. Applied Surface Science. ISSN 0169-4332. 435, p. 1213–1219. doi: 10.1016/j.apsusc.2017.11.221.
Hofmann, Philip; Ugeda, Miguel; Martınez-Galera, Antonio; Strozecka, Anna; Gomez-Rodrıguez, Jose & Rienks, Emile [Show all 9 contributors for this article] (2017). Strong-coupling charge density wave in a one-dimensional topological metal. arXiv.org. ISSN 2331-8422. doi: 10.1103/physrevb.99.035438.
Nowakowska, Sylwia; Mazzola, Federico; Alberti, Mariza N.; Song, Fei; Voigt, Tobias & Nowakowski, Jan [Show all 29 contributors for this article] (2017). Adsorbate-Induced Modification of the Confining Barriers in a Quantum Box Array. ACS Nano. ISSN 1936-0851. 12(1), p. 768–778. doi: 10.1021/acsnano.7b07989.
Jorge, Marina; Cooil, Simon Phillip; Edmonds, Mark; Thomsen, Lars; Nematollahi, Mohammadreza & Mazzola, Federico [Show all 7 contributors for this article] (2017). Accelerated ageing of molybdenum oxide. Materials Research Express. ISSN 2053-1591. 4(11). doi: 10.1088/2053-1591/aa9287.
Vinje, Jakob; Falck, Merete; Mazzola, Federico; Cooil, Simon Phillip; Koch, Henrik & Høyvik, Ida-Marie [Show all 7 contributors for this article] (2017). Tautomerization of thymine using ultraviolet light. Langmuir. ISSN 0743-7463. 33(38), p. 9666–9672. doi: 10.1021/acs.langmuir.7b02473.
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.
Mazzola, Federico; Frederiksen, Thomas; Balasubramanian, Thiagarajan; Hofmann, Philip; Hellsing, Bo & Wells, Justin (2017). Strong electron-phonon coupling in the σ band of graphene. Physical review B (PRB). ISSN 2469-9950. 95(7). doi: 10.1103/PhysRevB.95.075430.
Shen, Kongchao; Narsu, Bai; Ji, Gengwu; Sun, Haoliang; Hu, Jinbang & Liang, Zhaofeng [Show all 14 contributors for this article] (2017). On-surface manipulation of atom substitution between cobalt phthalocyanine and the Cu(111) substrate. RSC Advances. ISSN 2046-2069. 7(23), p. 13827–13835. doi: 10.1039/c7ra00636e. Full text in Research Archive
Cooil, Simon Phillip; Mazzola, Federico; Klemm, Hagen W; Peschel, Gina; Niu, Yuran R & Zakharov, Alexei A [Show all 11 contributors for this article] (2017). In Situ Patterning of Ultrasharp Dopant Profiles in Silicon. ACS Nano. ISSN 1936-0851. 11(2), p. 1683–1688. doi: 10.1021/acsnano.6b07359.
Jorge, Marina; Polyakov, Stanislav; Cooil, Simon Phillip; Schenk, Alex Kevin; Edmonds, Mark & Thomsen, Lars [Show all 8 contributors for this article] (2017). Robust p-type doping of copper oxide using nitrogen implantation. Materials Research Express. ISSN 2053-1591. 4(7). doi: 10.1088/2053-1591/aa7613. Show summary
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.
Bawden, L; Cooil, Simon Phillip; Mazzola, Federico; Riley, JM; Collins-Mcintyre, LJ & Sunko, V [Show all 15 contributors for this article] (2016). Spin-valley locking in the normal state of a transition-metal dichalcogenide superconductor. Nature Communications. ISSN 2041-1723. 7. doi: 10.1038/ncomms11711. Full text in Research Archive
Cooil, Simon Phillip; Mørtsell, Eva Anne; Mazzola, Federico; Jorge, Marina; Wenner, Sigurd & Edmonds, M T [Show all 15 contributors for this article] (2016). Thermal migration of alloying agents in aluminium. Materials Research Express. ISSN 2053-1591. 3(11). doi: 10.1088/2053-1591/3/11/116501. Show summary
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 [Show all 7 contributors for this article] (2015). Resonant photoemission spectroscopy for intermediate band materials. Applied Physics Letters. ISSN 0003-6951. 107:192102(19). doi: 10.1063/1.4935536. Show summary
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 [Show all 7 contributors for this article] (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. Show summary
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.
Bawden, Lewis; Riley, Jonathan; Kim, Choong; Sankar, Raman; monkman, Eric & Shai, Daniel [Show all 18 contributors for this article] (2015). Hierarchical spin-orbital polarization of a giant Rashba system. Science Advances. ISSN 2375-2548. 1(8). doi: 10.1126/sciadv.1500495.
Mazzola, Federico; Trinh, Thuat; Cooil, Simon, Phillip; Østli, Elise Ramleth; Høydalsvik, Kristin & Skjønsfjell, Eirik Torbjørn Bakken [Show all 12 contributors for this article] (2015). Graphene coatings for chemotherapy: avoiding silver-mediated degradation. 2D Materials. ISSN 2053-1583. 2(2). doi: 10.1088/2053-1583/2/2/025004.
Bianchi, M; Song, F; Cooil, Simon Phillip; Monsen, Åsmund Fløystad; Wahlström, Erik & Miwa, JA [Show all 14 contributors for this article] (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.
Song, Fei; Wells, Justin; Jiang, Zheng; Saxegaard, Magne & Wahlström, Erik (2015). Low-temperature growth of bismuth thin films with (111) facet on highly oriented pyrolytic graphite. ACS Applied Materials & Interfaces. ISSN 1944-8244. 7(16), p. 8525–8532. doi: 10.1021/acsami.5b00264.
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), p. 8438–8450. doi: 10.1039/c5nr00674k. Full text in Research Archive
Røst, Håkon; Mazzola, Federico; Bakkelund, Johannes; Åsland, Anna Cecilie; Hu, Jinbang & Cooil, Simon Phillip [Show all 8 contributors for this article] (2014). Disentangling electron-boson interactions on the surface of a familiar ferromagnet. Physical review B (PRB). ISSN 2469-9950. 109, p. 1–9. doi: 10.1103/PhysRevB.109.035137. Full text in Research Archive
Riley, Jon; Mazzola, Federico; Dendzik, M; Michiardi, M; Takayama, T & Bawden, L [Show all 17 contributors for this article] (2014). Direct observation of spin-polarized bulk bands in an inversion-symmetric semiconductor. Nature Physics. ISSN 1745-2473. 10(11), p. 835–839. doi: 10.1038/nphys3105.
Mazzola, Federico; Edmonds, Mark; Høydalsvik, Kristin; Carter, Damien; Marks, Nigel & Cowie, Bruce [Show all 10 contributors for this article] (2014). Determining the electronic confinement of a subsurface metallic state. ACS Nano. ISSN 1936-0851. 8(10), p. 10223–10228. doi: 10.1021/nn5045239.
Mazzola, Federico; Polley, Craig; Miwa, JA; Simmons, MY & Wells, Justin (2014). Disentangling phonon and impurity interactions in δ-doped Si(001). Applied Physics Letters. ISSN 0003-6951. 104(17). doi: 10.1063/1.4874651.
Monsen, Åsmund Fløystad; Boschker, Jos Emiel; Macia, F; Wells, Justin; Nordblad, Per & Kent, Andrew D. [Show all 9 contributors for this article] (2014). Thickness dependence of dynamic and static magnetic properties of pulsed laser deposited La(0.7)Sr(0.3)MnO(3)films on SrTiO(3)(001). Journal of Magnetism and Magnetic Materials. ISSN 0304-8853. 369, p. 197–204. doi: 10.1016/j.jmmm.2014.06.038.

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Pacáková, Barbara; Matejdes, Marian; Wagner, Daniel; Michels Brito, Paulo Henrique; Seljelid, Konstanse Kvalem & Michels Brito Miranda, Leander Edward [Show all 10 contributors for this article] (2023). SYNCHRONOUS SYNTHESIS OF NITROGEN-DOPED GRAPHENE AND CARBON NANOTUBES IN A NANOLAYERED SILICATE.
Pacáková, Barbara; Matejdes, Marian; Wagner, Daniel; Michels Brito, Paulo Henrique; Seljelid, Konstanse Kvalem & Michels Brito Miranda, Leander Edward [Show all 10 contributors for this article] (2023). Carbon Nanotubes and Graphene Flakes Grown Synchronously in the Confined 2D Nanospace of a Layered Silicate .
Røst, Håkon; Tosi, Ezequiel; Strand, Frode Sneve; Åsland, Anna Cecilie; Lacovig, Paolo & Lizzit, Silvano [Show all 7 contributors for this article] (2023). Determining the Arrangement of Subsurface Dopants in a Silicon Quantum Device Platform.
Tosi, Ezequiel; Strand, Frode Sneve; Åsland, Anna Cecilie; Lacovig, Paolo; Lizzit, Silvano & Wells, Justin William (2023). Probing the Atomic Arrangement of Sub-Surface Dopants in a Silicon Quantum Device Platform. Show summary
Recently, efforts to realize a silicon-based, CMOS-compatible quantum computer have been intensifying. Central to its development are so-called Si:P δ-layers: i.e., ultra-sharp layers of phosphorus atoms placed beneath the silicon surface. Until recently, one key property has remained elusive: the arrangement of the P dopants within the δ-layer. The answer to this question is of crucial importance, as the dopant arrangement will directly impact the energy separation (i.e., valley-splitting) of the supported quantum well states. In this talk, we will demonstrate how the local neighborhood around encapsulated dopants in a bulk semiconductor can be directly probed using X-ray photoelectron diffraction (XPD). By utilizing subtle core level energy shifts that are concomitant with the coordination of a dopant, chemically specific diffractive images can be formed. Through comparison with XPD simulations that are derived from models of the local atomic environment around the dopants, the true dopant atom placement can be ascertained. Typically, XPD is only used as a probe of surface structure. We demonstrate here that – under the right conditions, it also can be used to determine the local arrangement of sub-surface atoms. Therefore, XPD is well suited for solving the long-standing mystery of the Si:P δ-layer structure.
Jensen, Ingvild Julie Thue; Thøgersen, Annett; Cooil, Simon Phillip; Wells, Justin William; Prytz, Øystein & Von Wenckstern, Holger (2023). Bandgap and band offset engineering in κ-Ga2O3-based thin films (Invited talk)).
Pacáková, Barbara; Matejdes, Marian; Wagner, Daniel; Michels Brito, Paulo Henrique; Seljelid, Konstanse Kvalem & Michels, Leander [Show all 10 contributors for this article] (2022). Graphene confined in layered silicate.
Pacáková, Barbara; Matejdes, Marian; Wagner, Daniel; Michels Brito, Paulo Henrique; Seljelid, Konstanse Kvalem & Michels, Leander [Show all 10 contributors for this article] (2022). Graphene confined in layered silicate.
Pacáková, Barbara; Matejdes, Marian; Wagner, Daniel; Michels Brito, Paulo Henrique; Seljelid, Konstanse Kvalem & Michels, Leander [Show all 10 contributors for this article] (2022). Carbon Nanotubes and Graphene Flakes Grown Synchronously in the Confined 2D Nanospace of a Layered Silicate.
Mæland, Kristian; Røst, Håkon Ivarssønn; Wells, Justin W & Sudbø, Asle (2022). S68.00011: Electron-magnon coupling and quasiparticle lifetimes on the surface of a topological insulator.
Jacobsen, Sol; Brataas, Arne & Wells, Justin W (2021). Presentation of QuSpin, for Technoport Tech Dives .
Wells, Justin (2019). Angle Resolved UPS, general introduction and its possibilities.
Wells, Justin (2019). Carrots, Meteorites and Quantum Mechanics.
Wells, Justin (2019). "The Electronic Bandstructure of Atomically Sharp Dopant Structures in Silicon".
Sunding, Martin Fleissner; Jensen, Ingvild Julie Thue; Svenum, Ingeborg-Helene; Ivashenko, Oleksii; Redekop, Evgeniy & Wells, Justin [Show all 11 contributors for this article] (2019). National Surface and Interface Analysis Laboratory (NICE II): From (near) in-situ to operando XPS analysis.
Chellappan, Rajesh Kumar; Cooil, Simon Phillip; Dahl, Oystein & Wells, Justin (2019). Insitu study of graphene patterning on SiC.
Wells, Justin (2018). The electronic band structure of delta doped silicon.
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.
Schenk, Alex Kevin; Pakpour-Tabrizi, Alex; Mazzola, Federico; Holt, Ann Julie; Nyborg, Thomas & Cooil, Simon Phillip [Show all 13 contributors for this article] (2018). Using ARPES as a tool for exploring quantisation in delta-doped silicon and diamond.
Røst, Håkon Ivarssønn; Chellappan, Rajesh Kumar; Tadich, Anton; Dahl, Øystein & Wells, Justin (2018). Preparation of Transfer-Free Graphene on Insulator for Novel Electronic Devices.
Wells, Justin (2018). Graphene and silicon: creating and understanding 2D structures and properties using silicon-compatible fabrication.
Wells, Justin (2018). Exploring the electronic structure of artificial 2D metals; a novel playground for experimentalists.
Wells, Justin (2018). Understanding thermal migration of alloying agents.
Wells, Justin (2018). Exploring the nanoscale playground; from cancer therapy to quantum computing.
Wells, Justin (2018). Probing the electron-phonon interaction in graphene: an experimental perspective.
Wells, Justin (2018). Engineering novel 2D materials for quantum device applications.
Chellappan, Rajesh Kumar; Cooil, Simon; Dahl, Oystein & Wells, Justin (2017). In-situ study of graphene patterning on SiC.
Wells, Justin (2017). In Situ Patterning of Ultrasharp Dopant Profiles in Silicon.
Vinje, Jakob; Beckwith, Kai Sandvold; Cooil, Simon Phillip; Wells, Justin & Sikorski, Pawel (2017). Nano-structured surfaces and controlled surface chemistry for cell studies.
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.
Jorge, Marina; Wells, Justin; Polyakov, Stanislav; Nematollahi, Mohammadreza & Cooil, Simon (2016). A new generation of abundant and low-toxicity photovoltaic materials.
Michels, Leander; Patil, Nilesh; Cooil, Simon, Phillip; Coucheron, David Andre; Fokine, Michael & Schleputz, Christian [Show all 9 contributors for this article] (2016). SiGe in confined fiber geometry.
Wells, Justin (2015). Supermaterialet grafén kan gi bedre kreftbehandling. Gemini. ISSN 0802-085X.
Wells, Justin (2015). Catheter studies raise acid alert. Nanotechweb.org.
Wells, Justin (2015). Improving the delivery of chemotherapy with graphene. Institute of Physics Newsletter. doi: 10.1088/2053-1583/2/2/025004.
Wells, Justin (2015). KVANTEDATAMASKINER: Så viktig er gjennombruddet i kvantedatamaskiner. Teknisk Ukeblad. ISSN 0040-2354.
Wells, Justin (2015). Engineering metallic states in silicon for quantum computation applications.
Wells, Justin (2015). Graphene coatings for chemotherapy; Avoiding silver-mediated degradation.
Wells, Justin (2015). The ever expanding photoemission toolbox.
Wells, Justin (2015). The ever expanding photoemission toolbox.
Wells, Justin (2015). Some things you thought you knew, and some things you probably didn’t - a physicists view of the world.
Wells, Justin (2015). Electron phonon mediated transitions in 2D materials; towards a designer superconductor?
Wells, Justin (2015). Towards designer 2D materials.
Wells, Justin (2015). Photoelectron Spectroscopies.
Wells, Justin (2015). Avoiding degradation of chemotherapy drugs: Is graphene the answer? Nanomedicine. ISSN 1743-5889. 10(22), p. 3307–3310. doi: 10.2217/nnm.15.142.
Trinh, Thuat; Mazzola, Federico; Kjelstrup, Signe & Wells, Justin (2015). DEGRADATION OF 5-FLUOROURACIL (A CANCER DRUG) ON Ag(111) AND GRAPHENE SURFACE: A DFT STUDY.
Wells, Justin & Brandslet, Steinar (2014). Ett Skritt Nærmere Kvantedatamaskiner. Gemini. ISSN 0802-085X.
Wells, Justin & Fremstad, Jon Marius (2014). Spinntronikkens Reodor Felgen. Under dusken : studentavisa i Trondheim. ISSN 0807-0768.
Wells, Justin & Ulvestad, Lars (2014). Melder to store gjennombrudd i kvantedata, påen måned. Teknisk Ukeblad. ISSN 0040-2354.
Wells, Justin & Ulvestad, Lars (2014). KVANTEDATAMASKINER: NTNU-forskere vil bruke silisium til kvantedatabehandling. Teknisk Ukeblad. ISSN 0040-2354.
Wells, Justin & Ulvestad, Lars (2014). D-WAVE: Er det såvanskelig åbevise at kvantedata fungerer? Teknisk Ukeblad. ISSN 0040-2354.

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Published Sep. 10, 2020 9:49 AM - Last modified Sep. 15, 2023 2:50 PM

Projects

Diamond and Gallium Oxide Interfaces for Power Electronics Devices (DOPED)

Research groups

Semiconductor Physics