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| 2. |
- Glasbey, JC, et al.
(author)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
- Kuehne, P, et al.
(author)
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Polarization Selection Rules for Inter-Landau-Level Transitions in Epitaxial Graphene Revealed by the Infrared Optical Hall Effect
- 2013
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 111:7, s. e077402-
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Journal article (peer-reviewed)abstract
- We report on the polarization selection rules of inter-Landau-level transitions using reflection-type optical Hall effect measurements from 600 to 4000 cm-1 on epitaxial graphene grown by thermal decomposition of silicon carbide. We observe symmetric and antisymmetric signatures in our data due to polarization preserving and polarization mixing inter-Landau-level transitions, respectively. From field-dependent measurements, we identify that transitions in coupled graphene monolayers are governed by polarization mixing selection rules, whereas transitions in decoupled graphene monolayers are governed by polarization preserving selection rules. The selection rules may find explanation by different coupling mechanisms of inter-Landau-level transitions with free charge carrier magneto-optic plasma oscillations.
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| 5. |
- Grubisic-Cabo, Antonija, et al.
(author)
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Magnesium-intercalated graphene on SiC : Highly n-doped air-stable bilayer graphene at extreme displacement fields
- 2021
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 541
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Journal article (peer-reviewed)abstract
- We use angle-resolved photoemission spectroscopy to investigate the electronic structure of bilayer graphene at high n-doping and extreme displacement fields, created by intercalating epitaxial monolayer graphene on silicon carbide with magnesium to form quasi-freestanding bilayer graphene on magnesium-terminated silicon carbide. Angle-resolved photoemission spectroscopy reveals that upon magnesium intercalation, the single massless Dirac band of epitaxial monolayer graphene is transformed into the characteristic massive double-band Dirac spectrum of quasi-freestanding bilayer graphene. Analysis of the spectrum using a simple tight binding model indicates that magnesium intercalation results in an n-type doping of 2.1 x 10(14) cm(-2) and creates an extremely high displacement field of 2.6 V/nm, thus opening a considerable gap of 0.36 eV at the Dirac point. This is further confirmed by density-functional theory calculations for quasi-freestanding bilayer graphene on magnesium-terminated silicon carbide, which show a similar doping level, displacement field and bandgap. Finally, magnesium-intercalated samples are surprisingly robust to ambient conditions; no significant changes in the electronic structure are observed after 30 min exposure to air.
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| 6. |
- Panchal, V., et al.
(author)
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Atmospheric doping effects in epitaxial graphene: correlation of local and global electrical studies
- 2016
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In: 2D Materials. - : IOP Publishing. - 2053-1583. ; 3:1
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Journal article (peer-reviewed)abstract
- We directly correlate the local (20 nm scale) and global electronic properties of a device containing mono-, bi- and tri-layer epitaxial graphene (EG) domains on 6H-SiC (0001) by simultaneously performing local surface potential measurements using Kelvin probe force microscopy and global transport measurements. Using well-controlled environmental conditions we investigate the doping effects of N-2, O-2, water vapour and NO2 at concentrations representative of the ambient air. We show that presence of O-2, water vapour and NO2 leads to p-doping of all EG domains. However, the thicker layers of EG are significantly less affected. Furthermore, we demonstrate that the general consensus of O-2 and water vapour present in ambient air providing majority of the p-doping to graphene is a common misconception. We experimentally show that even the combined effect of O-2, water vapour, and NO2 at concentrations higher than typically present in the atmosphere does not fully replicate p-doping from ambient air. Thus, for EG gas sensors it is essential to consider naturally occurring environmental effects and properly separate them from those coming from targeted species.
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