The removal of Ag on top of the multilayer silicene surface by deuterium atom absorption

• Main Authors: Chien, Ko Hsiang, 錢可翔
• Other Authors: Lin, Deng Sung
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/35641965169102686385

碩士 === 國立清華大學 === 物理系 === 103 === This thesis reports and discusses the atomic structure of the (〖√3×√3)〗_si silicene surface. This surface structure is common to all so-called multi-layer silicene film. Our experimental approach is to expose the (〖√3×√3)〗_si silicene film with deuterium atomic beam and to observe the resulting film morphology by low-temperature scanning tunneling spectroscopy (LT-STM). The experiment results reveal that deuterium is absorbed on Si atom to form one-dimension D/Si chains, which are randomly aligned in three of Ag [101 ̅] directions. The separation of these D/Si chains is 2a, where “a” is the lattice constant of Si (111) crystal, 3.84 Å. Some atoms are expelled from (〖√3×√3)〗_si silicene surface and form 3D islands. The height difference of these 3D islands are an integer multiple of Ag (111) step height. The corresponding STS spectra measurement on the islands show the Coulomb blockade effect. Therefore, that atoms forming the 3D islands are verified as Ag. The surface morphology after deuterium adsorption on the “multilayer silicene” is highly similar to that of H/(√3×√3)Ag-Si (111) studied by Oura et al. These findings imply our experiment result is compatible with the Ag-on-top model claimed by Shirai et al.. In summary, we found the so-called multilayer silicene should be rectified as (〖√3×√3)〗_si Si(111)/Ag (111). In the other words, the so-called (〖√3×√3)〗_si silicene is likely an ultra-thin Si (111) film with Ag on its surface.