| 1. |
- Hetzel, M., et al.
(författare)
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Nanowire Reconstruction on the 4H-SiC(1-102) Surface
- 2007
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Ingår i: Silicon Carbide and Related Materials 2006. - : Trans Tech Publications Inc.. ; , s. 529-532
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Konferensbidrag (refereegranskat)abstract
- Ordered reconstruction phases on the 4H-SiC(1102) surface have been investigated usinglow-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunnelingmicroscopy (STM). After initial hydrogen etching, the samples were prepared by Si deposition andannealing in ultra-high vacuum (UHV). Two distinct reconstruction phases develop upon annealing,first with a (2×1), and at higher temperatures with a c(2×2) LEED pattern. After further annealingthe fractional order LEED spots vanish and a (1x1) pattern develops. For the (2×1) phase, STMmicrographs show that adatom chains develop on large flat terraces, which in view of AES consistof additional Si. These highly linear and equidistant chains represent a self-assembled well-orderedpattern of nanowires developing due to the intrinsic structure of the 4H-SiC(1102) surface. For thec(2×2) phase AES indicates a surface composition close to the bulk stoichiometry. For the (1×1)phase a further Si depletion is observed.
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| 2. |
- Nguyen, Thi Thuy Nhung, et al.
(författare)
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Topological Surface State in Epitaxial Zigzag Graphene Nanoribbons
- 2021
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 21:7, s. 2876-2882
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Tidskriftsartikel (refereegranskat)abstract
- Protected and spin-polarized transport channels are the hallmark of topological insulators, coming along with an intrinsic strong spin-orbit coupling. Here we identified such corresponding chiral states in epitaxially grown zigzag graphene nanoribbons (zz-GNRs), albeit with an extremely weak spin-orbit interaction. While the bulk of the monolayer zz-GNR is fully suspended across a SiC facet, the lower edge merges into the SiC(0001) substrate and reveals a surface state at the Fermi energy, which is extended along the edge and splits in energy toward the bulk. All of the spectroscopic details are precisely described within a tight binding model incorporating a Haldane term and strain effects. The concomitant breaking of time-reversal symmetry without the application of external magnetic fields is supported by ballistic transport revealing a conduction of G = e2/h.
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| 3. |
- Virojanadara, Chariya, et al.
(författare)
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Atomic and Electronic Structure of the (2x1) and c(2x2) 4H-SiC(1(1)over-bar02) Surfaces
- 2008
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2007, PTS 1 AND 2. - : Trans Tech Publications Inc.. ; , s. 291-296
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Konferensbidrag (refereegranskat)abstract
- The atomic and electronic structure of 4H-SiC(1 1 02) surfaces were investigated usingscanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and photoemission(PES). Two well ordered phases existing on this surface, i.e. (2×1) and c(2×2) are discussed. The(2×1) phase consists of a Si adlayer which is topped by an array of ordered Si-nanowires withelectronic states confined to one dimension. For the c(2×2) phase STM indicates the presence ofadatoms and PES a surface composition close to bulk SiC stoichiometry. A detailed atomic modelfor this c(2×2) phase is proposed.
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