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Wang, Weimin
Publications (3 of 3) Show all publications
Wang, W., Olovsson, W. & Uhrberg, R. (2016). Band structure of hydrogenated silicene on Ag(111): Evidence for half-silicane. PHYSICAL REVIEW B, 93(8), 081406
Open this publication in new window or tab >>Band structure of hydrogenated silicene on Ag(111): Evidence for half-silicane
2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, no 8, p. 081406-Article in journal (Refereed) Published
Abstract [en]

In the case of graphene, hydrogenation removes the conductivity due to the bands forming the Dirac cone by opening up a band gap. This type of chemical functionalization is of the utmost importance for electronic applications. As predicted by theoretical studies, a similar change in the band structure is expected for silicene, the closest analog to graphene. We here report a study of the atomic and electronic structures of hydrogenated silicene with hydrogen on one side, the so-called half-silicane. The ("2 root 3 x 2 root 3") phase of silicene on Ag(111) was used in this Rapid Communication since it can be formed homogeneously across the entire surface of the Ag substrate. Low-energy electron diffraction and scanning tunneling microscopy data clearly show that hydrogenation changes the structure of silicene on Ag(111) resulting in a (1 x 1) periodicity with respect to the silicene lattice. The hydrogenated silicene also exhibits a quasiregular ("2 root 3 x 2 root 3")-like arrangement of vacancies. Angle-resolved photoelectron spectroscopy revealed two dispersive bands which can be unambiguously assigned to half-silicane. The common top of these bands is located at similar to 0.9 eV below the Fermi level. We find that the experimental bands are closely reproduced by the theoretical band structure of free-standing silicene with H adsorbed on the upper hexagonal sublattice.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-125672 (URN)10.1103/PhysRevB.93.081406 (DOI)000369729000001 ()
Note

Funding Agencies|Swedish Research Council (VR) [621-2010-3746, 621-2014-4764, 621-2011-4426]; Linkoping Linnaeus Initiative for Novel Functional Materials - Swedish Research Council (VR) [2008-6582]; Swedish National Infrastructure for Computing (SNIC)

Available from: 2016-03-02 Created: 2016-02-29 Last updated: 2016-03-29
Wang, W., Olovsson, W. & Uhrberg, R. (2015). Experimental and theoretical determination of sigma bands on ("2 root 3 x 2 root 3") silicene grown on Ag(111). Physical Review B. Condensed Matter and Materials Physics, 92(20), 205427
Open this publication in new window or tab >>Experimental and theoretical determination of sigma bands on ("2 root 3 x 2 root 3") silicene grown on Ag(111)
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 20, p. 205427-Article in journal (Refereed) Published
Abstract [en]

Silicene, the two-dimensional (2D) allotrope of silicon, has very recently attracted a lot of attention. It has a structure that is similar to graphene and it is theoretically predicted to show the same kind of electronic properties which have put graphene into the focus of large research and development projects worldwide. In particular, a 2D structure made from Si is of high interest because of the application potential in Si-based electronic devices. However, so far there is not much known about the silicene band structure from experimental studies. A comprehensive study is here presented of the atomic and electronic structure of the silicene phase on Ag(111) denoted as (2 root 3 x 2 root 3)R30 degrees in the literature. Low energy electron diffraction (LEED) shows an unconventional rotated ("2 root 3 x 2 root 3") pattern with a complicated set of split diffraction spots. Scanning tunneling microscopy (STM) results reveal a Ag(111) surface that is homogeneously covered by the ("2 root 3 x 2 root 3") silicene which exhibits an additional quasiperiodic long-range ordered superstructure. The complex structure, revealed by STM, has been investigated in detail and we present a consistent picture of the silicene structure based on both STM and LEED. The homogeneous coverage by the ("2 root 3 x 2 root 3") silicene facilitated an angle-resolved photoelectron spectroscopy study which reveals a silicene band structure of unprecedented detail. Here we report four silicene bands which are compared to calculated dispersions based on a relaxed (2 root 3 x 2 root 3) model. We find good qualitative agreement between the experimentally observed bands and calculated silicene bands of sigma character.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123801 (URN)10.1103/PhysRevB.92.205427 (DOI)000365509100011 ()
Note

Funding Agencies|Swedish Research Council [621-2010-3746, 621-2014-4764, 621-2011-4426, 2008-6582]; Linkoping Linnaeus Initiative for Novel Functional Materials; Swedish National Infrastructure for Computing (SNIC)

Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2017-11-30
Wang, W., Sohail, H. M., Osiecki, J. & Uhrberg, R. (2014). Broken symmetry induced band splitting in the Ag2Ge surface alloy on Ag(111). Physical Review B. Condensed Matter and Materials Physics, 89(12), 125410-1-125410-6
Open this publication in new window or tab >>Broken symmetry induced band splitting in the Ag2Ge surface alloy on Ag(111)
2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 12, p. 125410-1-125410-6Article in journal (Refereed) Published
Abstract [en]

We report a study of the atomic and electronic structures of the ordered Ag2Ge surface alloy containing ⅓ monolayer of Ge. Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and angle-resolved photoelectron spectroscopy (ARPES) data reveal a symmetry breaking of the expected √3 × √3 periodicity, which is established for other Ag2M alloys (M = Bi, Sb, Pb, and Sn). The deviation from a simple √3 × √3 structure manifests itself as a splitting of diffraction spots in LEED, as a striped structure with a 6× periodicity including a distortion of the local hexagonal structure in STM, and as a complex surface band structure in ARPES that is quite different from those of the other Ag2M alloys. These results are interesting in view of the differences in the atomic and electronic structures exhibited by different group IV elements interacting with Ag(111). Pb and Sn form √3 × √3 surface alloys on Ag(111), of which Ag2Pb shows a surface band structure with a clear spin-orbit split. Si and C form silicene and graphene structures, respectively, with linear band dispersions and the formation of Dirac cones as reported for graphene. The finding that Ag2Ge deviates from the ideal (√3 × √3) Ag2Sn and Ag2Pb surface alloys makes Ge an interesting “link” between the heavy group IV elements (Sn, Pb) and the light group IV elements (Si, C).

Place, publisher, year, edition, pages
American Physical Society, 2014
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-105259 (URN)10.1103/PhysRevB.89.125410 (DOI)000332460600003 ()
Available from: 2014-03-14 Created: 2014-03-14 Last updated: 2018-03-16Bibliographically approved
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