Ab initio calculations of structural and electronic properties of 6H-SiC(0001) surfaces

Sabisch, M.; Krüger, Peter; Pollmann, J.

doi:10.1103/physrevb.55.10561

Cited by 120 publications

(100 citation statements)

References 34 publications

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“…Similar results are obtained for sample voltages with magnitudes in the range 0.8-2.0 V. This combination of tunneling spectra and surface topography is clearly consistent with what is expected for a T 4 Si adatom model. Furthermore, it is inconsistent with other models of the surface which involve vacancies [27], trimers [25,29] or more complicated entities since there, we would expect either metallic bands or the empty and filled states at different spatial locations or both. Our results are unable to distinguish between Si and C adatoms, T 4 and H 3 adatoms, or discern rearrangements of the bulk layers beneath the adatoms, but nevertheless are strongly in favor of a MottHubbard model since the empty and filled states are spatially coincident.…”

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 39%

“…The states at about 1 eV above and below the Fermi level we identify with those seen in PES and IPES. The origin of the state observed at 1.9 eV above E F is not clear at present, although it may be associated with one of the many surface resonances which occur on this surface [29]. For p-type material, at large currents we again see a mostly featureless spectrum with a strong feature D 2 at large positive voltages.…”

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 69%

“…The fourth bonding orbital extends into vacuum with only one electron in it. Local density functional calculations for this structural model [28,29] predict a half-filled, and hence metallic band arising from the dangling bond. More refined computations employed a two-dimensional Hubbard model and indicated that the energy levels of this surface consist of a filled and an empty band, separated by a Hubbard gap of U=1.6 eV, thus producing a semiconducting density of states (DOS).…”

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 99%

“…Several workers have studied the atomic structure of the surface using the scanning tunneling microscope (STM) [25,26]. A set of reconstructions of the Si terminated (0001) surface has been discovered, one of which, the √3×√3, has evoked much experimental [15,16,27] and theoretical [17,[28][29][30] interest. Theoretically, the lowest energy model for this reconstruction consists of Si adatoms at T 4 positions on a Si terminated bulk crystal.…”

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 99%

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Recent developments in scanning tunneling spectroscopy of semiconductor surfaces

2001

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Several recent developments in scanning tunneling spectroscopy (STS) of semiconductor surfaces are reviewed. First, the normalization of spectra is discussed, which for the Si(111)2×1 surface is found to produce a small shift in the apparent position of band edges. With this correction, the surface band gap measured by STS is found to be in good agreement with that obtained by other experimental and theoretical techniques. Second, it is shown for the SiC(0001)√3×√3 surface that the tunneling spectra show a remarkable evolution with decreasing current, and at pA levels they reveal a Mott-Hubbard gap for the surface states, in agreement with that seen by other methods. Finally, a detailed discussion is presented on the absence of electronic effects for the tunnel current into empty states of III-V (110) cleaved surfaces. From this result it is demonstrated that one can use observed strain induced displacements of such surfaces to yield information on the chemical composition of the underlying material. I IntroductionSince the early days of the scanning tunneling microscopy (STM), spectroscopy of semiconductor surfaces has played an important role both in furthering our understanding of the the STM technique as well as in yielding new information about the surfaces themselves. For example, early voltage-dependent results on Si(111)2×1 and Si(111)7×7 surfaces enabled a determination of their structures and also illustrated the exquisite sensitivity of the STM to the surface states [1][2][3][4]. Complete conductance spectra as a function of tip-sample bias voltage clearly revealed the surface state bands. This early development of the scanning tunneling spectroscopy (STS) field has been reviewed [5].Slightly after the development of STS for semiconductor surface states, further studies were performed on cleaved GaAs(110) surface for which surface states do not play a large role in the results [6]. The difference in these two situations, with or without surface states, is quite dramatic. For Si(111)7×7 the surface state band is essentially metallic (i.e. no band gap), and the conductance dI/dV varies by less than three orders of magnitude over the voltage range −3 to +3 V. In contrast, for GaAs(110) a large band gap opens up in the spectrum and one requires 5-6 orders of magnitude in dynamic range to accurately measure the spectrum. Special techniques have been developed to achieve this high dynamic range [7]. For all of the direct gap III-V semiconductors, STS of the (110) surface can be used to reveal the bulk band gap as well as some other bulk critical point of the band structure [7]. Surface states make a small (but still noticeable) contribution of the spectra.Published in Appl. Phys. A 72 [Suppl.], S193 (2001).

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Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 39%

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 69%

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 99%

Section: Mott-hubbard Gap Of Sic(0001)√3×√3 Surfacementioning

confidence: 99%

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Recent developments in scanning tunneling spectroscopy of semiconductor surfaces

2001

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“…This relaxation is caused by bond-bending angular forces at the second-layer atoms, which affect C atoms stronger than Si atoms. The larger displacement of surface atoms on the C-face gives energy gain of 0.30 eV and on the Si-face the displacement is smaller and the energy gain is only 0.09 eV [11]. As a result the surface free energy of the C-face 6H-SiC is 718 erg/cm 2 and of the Siface is 1767 erg/cm 2 [12].…”

Section: Growth Of Cubic Sicmentioning

confidence: 72%

Cubic SiC formation on the C-face of 6H–SiC (0001) substrates

Vasiliauskas¹,

Juillaguet²,

Syväjärvi³

et al. 2012

Journal of Crystal Growth

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Abstract. Nucleation and subsequent growth of cubic SiC (111) on Si-and C-faces of nominally on-axis 6H-SiC substrates was investigated. More uniform nuclei and twin boundary distribution was observed when 3C-SiC was grown on the C-face. This was attributed to a lower critical supersaturation ratio. A new type of defects which appear as pits in the C-face 3C-SiC layers related to homoepitaxial 6H-SiC spiral growth was found and described. The evaluation of the growth driving force for both polar faces showed that the homoepitaxial 6H-SiC spirals were not overgrown on the C-face due to low maximum supersaturation ratio. The XRD ω-rocking characterization shows a better structural quality of the 3C-SiC was grown on the Si-face, however on the C-face the uniformity over the whole sample was higher. Unintentional doping by N (~10 16 cm -3 ) was slightly higher on the C-face while Al doping was higher (~10 14 cm -3 ) on the Si-face of the grown material, similarly to the doping of hexagonal SiC polytypes.

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Density Functional Study of Graphene Overlayers on SiC

Pankratov¹,

Mattausch²

2009

Silicon Carbide

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Ab initio calculations of structural and electronic properties of 6H-SiC(0001) surfaces

Cited by 120 publications

References 34 publications

Recent developments in scanning tunneling spectroscopy of semiconductor surfaces

Recent developments in scanning tunneling spectroscopy of semiconductor surfaces

Cubic SiC formation on the C-face of 6H–SiC (0001) substrates

Density Functional Study of Graphene Overlayers on SiC

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