V.Yu. Aristov

Pairs of Si atomic lines self-assembling on the β-SiC(100) surface: an 8×2 reconstruction

Abstract We investigate the transition between β -SiC(100) surface reconstructions using scanning tunneling microscopy (filled and empty electronic states). We find the unexpected formation of Si-dimer lines that are self-assembled by pairs with a long-range order resulting in an even 8×2 surface reconstruction. This very uncommon surface ordering results in the combination of alternating periodic 3×2 and 5×2 unit cells. In contrast to the β -SiC(100)3×2 surface reconstruction, the Si-dimers are symmetric. Such atomic line pairs provide a novel type of one dimensional sub-nanostructure potentially having interesting characteristics.

Cs‐induced highest EF jump above InAs(110) conduction‐band minimum

Upon room‐temperature deposition of minute amounts of Cs on InAs(110) surfaces, one induces probably the highest Fermi‐level pinning position (≊0.6 eV) for a semiconductor above the conduction‐band minimum. Synchrotron‐radiation core‐level photoemission spectroscopy was used to follow the Fermi‐level movement from the shift of the In 4d and As 3d core levels as a function of Cs coverages at room temperature. Already at very low coverages the Fermi level reaches an extremely high maximum above the conduction‐band minimum. The maximum of the Fermi‐level position correlates fairly well with the ionization energy of the individual atoms, as expected in the framework of the theory of donor‐type surface states induced by metallic adatoms. We thus consider that individual Cs adatoms produce donor‐type surface states placed at ≊0.6 eV above the conduction‐band minimum. This induces a very strong downward band bending which suggests the existence of a two‐dimensional electron gas at the open, nearly clean InAs(110) surface.

1D electronic properties in temperature-induced c(4×2) to 2×1 transition on the β-SiC(100) surface

Abstract We investigate the temperature-induced phase transition on Si-terminated β-silicon carbide (SiC)(100) surface using scanning tunneling microscopy (STM) and spectroscopy, and valence band and core level photoemission spectroscopies using synchrotron radiation. Above 700 K, the 2×1 surface exhibits metallization with a non-Fermi liquid power law shape spectral response near the Fermi level. This suggests a surface having one-dimensional (1D) metallicity related to the Si–Si dimers rows constituting the topmost atomic layer. This behavior can be related to the Luttinger liquid model.

High temperature dismantling of Si atomic lines on β-SiC(100)

We use high-temperature scanning tunneling microscopy (STM) to investigate the temperature-induced Si atomic line dynamics on the β-SiC(100) surface. These atomic lines are imaged up to 1200 K (probably the highest temperature STM imaging) and break at slightly higher temperatures. Their dismantling results from individual and collective atomic mechanisms including (i) one-by-one dimer removal, (ii) lateral motion of Si atomic lines and (iii) global surface migration of Si atoms resulting in two-dimensional island formation and melting at 1225 K. Overall, the results suggest that Si is thermally removed primarily at step edges.

Auger electron spectroscopy and low‐energy electron diffraction investigation of the InSb(110)+Ag system at 10–300 K with θ=0–20 monolayers

The Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) methods have been employed to study the film growth processes of the high‐vacuum‐cleaved InSb(110) surface at 10 and 300 K in the coverage interval from 0 to 20 monolayers (ML). The sample evolution in the process of heating up to room temperature after the Ag deposition at 8 K, and in the process of cooling down to 10 K after the deposition at 300 K has been investigated. A comparison of the Auger signals obtained in the process of deposition at 10 and 300 K, and in the process of heating of low‐temperature‐deposited samples has shown that at 10 K the depth distribution of the Ag atoms has a statistic character, and at room temperature the film growth is accompanied by the island formation. The conclusion on the In‐atom diffusion through the silver film is suggested by the interpretation of the Auger spectra, especially of those taken in the process of heating the samples. It is found that the deposition at 300 K leads only ...

H-Induced Si-Rich 3C-Si(100) 3x2 Surface Metallization

Atomic hydrogen interaction onto the 3C-SiC(100) 3x2 surface is investigated by synchrotron radiation based photoemission spectroscopies, atom resolved scanning tunneling microscopy and spectroscopy, and infrared absorption spectroscopy. Contrary to its wellknown role in semiconductor surface passivation, atomic hydrogen is found to metallize the 3C-SiC(100) 3x2 surface. This unexpected behavior results from an asymmetric attack of the Si-dimers located below the surface, leading to charge transfer and to metallization. Interestingly, the H-covered 3C-SiC(100) 3x2 surface metallization is not removed by oxygen.

Ag Growth on 3C-SiC(001) c(2x2) C-Terminated and c(4x2) Si-Terminated Surfaces

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Hydrogen Nanochemistry Achieving Clean and Pre-Oxidized Silicon Carbide Surface Metallization

We review H-induced metallization of clean and pre-oxidized 3C-SiC(100) 3x2 surfaces, the 1 st example of a semiconductor surface metallization by H. These investigations are based on core level and valence band photoemission spectroscopies using synchrotron radiation, infrared absorption spectroscopy, and scanning tunneling microscopy and spectroscopy. These results are also compared to recent ab-initio calculations. This unexpected behavior results from an asymmetric attack of Si-dimers located below the surface creating dangling bond defects and from H atoms terminating top-surface dangling bonds leading overall to large charge transfer to the surface and sub-surface regions.

Cubic SiC Surface Structure Studied by X-Ray Diffraction

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Silicon carbide surface structure investigated by synchrotron radiation-based x-ray diffraction

We use synchrotron radiation based x-ray diffraction at grazing incidence to study the atomic structure of Si-rich β-SiC(100) 3×2 surface reconstruction. The latter includes three different Si atomic planes, in qualitative agreement with the theoretical two adlayers asymmetric dimer model. The measurements provide an accurate determination of the atomic bond, indicating asymmetric Si dimers in the first plane, and an alternating long and short Si dimers subsurface organization in the second atomic plane responsible for the lack of dimers buckling in the first plane, unlike corresponding silicon or germanium surfaces.