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7 reconstruction during Ge/Si heteroepitaxial growthUozumi, Yuki; Yamazaki, Tatsuya*; Asaoka, Hidehito
no journal, ,
no abstracts in English
7 reconstruction during atomic hydrogen adsorptionUozumi, Yuki; Asaoka, Hidehito
no journal, ,
We have succeeded in measurements of the surface stress in Si(111) as a function of 77 reconstruction by comparison with the H-terminated Si(111) 11 surface. In order to obtain information on both the surface stress and the surface reconstruction simultaneously, we havecombined the surface-curvature and the reflection-high-electron-energy-diffraction instrumentations in an identical ultrahigh vacuum system. The stress evolution shows a decrease of tensile stresscorresponding to the formation of H-termination at the beginning of the atomic hydrogen exposure of Si(111) 77 surface. After the above treatment, a complete transformation of the surface structure occurs from the reconstructed surface to the 11 one. As a result, we find the Si(111) 11 surface releases 1.7 N/m (=J/m
), or (1.4 eV/(11 unit cell)), of the surface energy from the strong tensile Si(111) 77 reconstruction.
Terasawa, Tomoo
no journal, ,
Graphene, a two-dimensional material consisting of a honeycomb lattice of C atoms, has attracted much attention from basic physics to applications because of its extremely high carrier mobility and half-integer quantum Hall effect. Since a choice of substrate affects the properties of graphene, the synthesis and properties of graphene on various substrates have been the subject of surface science research. The interface between graphene and Au is expected in the field of spintronics because Au has a large atomic number and a large spin-orbit interaction. On the other hand, the atomic configuration in this interface is often unknown, and therefore, the angle-resolved photoemission spectroscopy (ARPES) experiments and density functional theory (DFT) calculations do not match each other for this interface. Here, we report the band structure of graphene on the Hex-Au(001) reconstructed surface using ARPES and DFT calculations. Since the solubility of C in Au is very low, graphene can be grown on Au surfaces by chemical vapor deposition (CVD). Hex-Au(001) reconstruction was kept even after the CVD growth of graphene. Therefore, the ARPES measurement was carried out for graphene on the well-known atomic configuration of Hex-Au(001). The ARPES intensity map shows the bandgap in the graphene pi band close to the Au 6sp band. The DFT calculated band structure shows the bandgap at the crossing point of the graphene pi and Au 6sp bands. We discuss that the bandgap originates from the hybridization between graphene and Au, similar to the case of graphene and Au interface on the SiC substrate. As the Rashba splitting of 100 meV was observed in the graphene and Au interface on the SiC substrate, we expect that the hybridization between graphene and Au is essential for the future applications of graphene for spintronic devices.