Electron correlation effects on SiC(111) and SiC(0001) surfaces

Bechstedt, F.; Furthmüller, J.

doi:10.1088/0953-8984/16/17/014

Cited by 29 publications

(20 citation statements)

References 47 publications

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“…Such MH transitions appear to be the rule rather than the exception on SiC surfaces ͑see, for example, Refs. 44 On the other hand, the question remains if the predicted metallicity of the interface, which is not experimentally observed, is a consequence of the artificially chosen ͑ ͱ 3 ϫ ͱ 3͒R30°unit cell in the calculations vs the much larger 6 ͱ 3 unit cell experimentally observed in LEED. An independent experimental estimate of the number of Si dangling bonds is provided by the S1/S2 ratio of 0.50Ϯ 0.08 ͓see Fig.…”

Section: A Interface Between Few Layer Graphene and Sic(0001)mentioning

confidence: 94%

Interaction, growth, and ordering of epitaxial graphene on SiC{0001} surfaces: A comparative photoelectron spectroscopy study

et al. 2008

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Thermally induced growth of graphene on the two polar surfaces of 6H-SiC is investigated with emphasis on the initial stages of growth and interface structure. The experimental methods employed are angle-resolved valence band photoelectron spectroscopy, soft x-ray induced core-level spectroscopy, and low-energy electron diffraction. On the Si-terminated ͑0001͒ surface, the ͑6 ͱ 3 ϫ 6 ͱ 3͒R30°reconstruction is the precursor of the growth of graphene and it persists at the interface upon the growth of few layer graphene ͑FLG͒. The ͑6 ͱ 3 ϫ 6 ͱ 3͒R30°structure is a carbon layer with graphene-like atomic arrangement covalently bonded to the substrate where it is responsible for the azimuthal ordering of FLG on SiC͑0001͒. In contrast, the interaction between graphene and the C-terminated ͑0001͒ surface is much weaker, which accounts for the low degree of order of FLG on this surface. A model for the growth of FLG on SiC͕0001͖ is developed, wherein each new graphene layer is formed at the bottom of the existing stack rather than on its top. This model yields, in conjunction with the differences in the interfacial bonding strength, a natural explanation for the different degrees of azimuthal order observed for FLG on the two surfaces.

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Section: A Interface Between Few Layer Graphene and Sic(0001)mentioning

confidence: 94%

Interaction, growth, and ordering of epitaxial graphene on SiC{0001} surfaces: A comparative photoelectron spectroscopy study

et al. 2008

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“…10,11,14,15 This is supported by the fact that for other reconstructions of the Si͑111͒-surface, as the Si͑111͒-͑3 ϫ 1͒ : Li, Si͑111͒-͑1 ϫ 1͒ : H, SiC͑111͒-͑3 ϫ 3͒, etc., correlation effects seem to modify substantially the single particle ͑electron͒ picture as well. 4,[15][16][17][18] The geometric and energetic properties of the ͑7 ϫ 7͒-reconstruction are well described within the DimerAdatom-Stackingfault ͑DAS͒ model. 6,[19][20][21][22] It leaves 19 dbs of the original 49 ones, one of the corner hole atom, 6 of the rest atoms, and 12 of the adatoms.…”

Section: Introductionmentioning

confidence: 99%

“…Despite an odd number of valence electrons per unit cell semiconductor surfaces may thus become ͑Mott-Hubbard͒ insulators. 3,4 The Si͑111͒-͑7 ϫ 7͒-reconstruction seems to be a counterexample; it stays metallic 4,5 since it eliminates a large fraction of its dbs ͑30 out of 49͒ by forming the ͑7 ϫ 7͒ structure. 6 Among the various reconstructions of the Si͑111͒-surface the ͑7 ϫ 7͒ one is not only by far the oldest example but also the best investigated one.…”

Section: Introductionmentioning

confidence: 99%

MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

et al. 2005

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Li adsorption at extremely low coverages ͑10 −3 ML and below͒ on the metallic Si͑111͒-͑7 ϫ 7͒ surface has been studied by ␤-NMR experiments ͑measurement of T 1 -times͒. Instead of increasing linearly with the sample temperature, as expected for a metallic system, the relaxation rate ␣ =1/T 1 is almost constant in between 50 K and 300 K sample temperature and rises considerably above. Comparison with T 1 -times around 900 K ͑ob-served with 6 Li-NMR͒ excludes adsorbate diffusion as the cause of the relaxation rate. Thus the almost temperature independent relaxation rate below 300 K points to an extremely localized and thus narrow band ͑width about 10 meV͒ which pins the Fermi energy. It is responsible for the metallicity of the ͑7 ϫ 7͒-reconstruction. Because of the steeply rising relaxation rate beyond 300 K this narrow band is located energetically within a gap ͑approximately 100-500 meV wide͒ in between a lower filled and an upper empty ͑Hubbard͒ band. Due to its extremely narrow width it can hardly be detected in photo electron experiments. In dynamical mean field theories based on Hubbard Hamiltonians this kind of density of states is typical for correlated electron systems close to a Mott-Hubbard metal-insulator transition.

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“…5,[11][12][13] SiC crystals exist in diverse stacking arrangements of the atomic planes such as hexagonal 6H and 4H and cubic 3C polytypes. Recently, SiC surfaces have attracted a lot of attention [14][15][16][17][18][19][20][21] due to their remarkable physical properties, which include a temperature-induced reversible structural and metal-insulator transition, 14 Mott-insulating surfaces, 15,16 self-organized one-dimensional Si chains, 17 and even a surprising hydrogen-induced metallization of a semiconductor surface. 18 Of special interest are the ͑100͒ surfaces of cubic SiC with Si termination, 3C-SiC͑100͒-3 ϫ 2 and 3C-SiC͑100͒-c͑4 ϫ 2͒.…”

Section: Introductionmentioning

confidence: 99%

Hydrogenation of semiconductor surfaces: Si-terminated cubic SiC(100) surfaces

Trabada

Ortega

2009

Phys. Rev. B

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We analyze the hydrogenation of the Si-terminated surfaces 3C-SiC͑100͒-3 ϫ 2 and 3C-SiC͑100͒-c͑4 ϫ 2͒ using density-functional-theory techniques. For the Si-rich 3 ϫ 2 case, after saturation of the Si dangling bonds, hydrogen atoms break Si-Si bonds between atoms in the first two layers, replacing them by Si-H bonds, up to a hydrogen adsorption of eight hydrogen atoms per 3 ϫ 2 unit cell, with the formation of SiH 3 groups on the surface. At higher hydrogen adsorptions Si-H bonds replace also Si-Si bonds between second-and third-layer Si atoms. We find that all the stable structures as a function of the hydrogen chemical potential are insulating and propose that the observed hydrogen-induced metallization of the Si-rich SiC͑100͒-3 ϫ 2 surface is related to the dynamical equilibrium between adsorption and abstraction of hydrogen atoms close to the point where hydrogen atoms start to break Si-Si bonds. We also find that desorption of SiH 4 molecules is not energetically favorable until values of the hydrogen chemical potential above half the energy of the H 2 molecule. Regarding the Si-poor c͑4 ϫ 2͒ surface, our results show that the hydrogenated H / SiC͑100͒-2 ϫ 1 surface corresponds to a monohydride surface with a Si coverage of one monolayer above the last C layer.

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Electron correlation effects on SiC(111) and SiC(0001) surfaces

Cited by 29 publications

References 47 publications

Interaction, growth, and ordering of epitaxial graphene on SiC{0001} surfaces: A comparative photoelectron spectroscopy study

Interaction, growth, and ordering of epitaxial graphene on SiC{0001} surfaces: A comparative photoelectron spectroscopy study

MetallicSi(111)−(7×7)-reconstruction: A surface close to a Mott-Hubbard metal-insulator transition

Hydrogenation of semiconductor surfaces: Si-terminated cubic SiC(100) surfaces

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