Single layer nickel disilicide on surface and as embedded layer

Single monolayers of various materials (e.g. graphene, silicene, bismuthene, plumbene, etc) have recently become fascinating and promising objects in modern condensed-matter physics and nanotechnology. However, growing a monolayer of non-layered material is still challenging. In the present report, it will be shown that single monolayer NiSi2 can be fabricated at Si(111) surface stabilized by either Tl, Pb or In monolayers. Nickel atoms were found to intercalate the stabilizing metal layers upon deposition and to reside in the interstitial sites inside the first silicon bilayer of bulk-like-terminated Si(111)1×1 surface. The interstitial positions almost coincide with the bulk NiSi2 atomic positions thus forming NiSi2 single layer. Atomic and electronic structure of formed systems is described in detail by means of a set of experimental techniques, including low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoemission spectroscopy and also first-principles density-functional-theory calculations. Quality of formed single monolayer NiSi2 was additionally confirmed by in situ four-probe transport measurements that show that single monolayer NiSi2 preserves a metallic-type conductivity down to 2.0 K. Moreover it was found that delta-type structure with atomic sheet of NiSi2 silicide embedded into a crystalline Si matrix can be fabricated using room-temperature overgrowth of a Si film onto the Tl stabilized NiSi2 surface layer. Confinement of the NiSi2 layer to a single atomic plane has been directly confirmed by high-resolution transmission electron microscopy

STM investigation of 2D alloys and compounds on Si(111) and Ge(111) surfaces

The work was supported by the Russian Science Foundation (Grant 14-12-00479)

Atomic structure and electronic properties of the two-dimensional (Au,Al)/Si(111)2×2 compound

[[sponsorship]]原子與分子科學研究所[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=1098-0121&DestApp=JCR&RQ=IF_CAT_BOXPLO

Electronic properties of the two-dimensional (Tl, Rb)/Si(1 1 1)√3x√3 compound having a honeycomb-like structure

Heavy metal layers having a honeycomb structure on the Si(1 1 1) surface were theoretically predicted to show prospects for possessing properties of the quantum spin Hall (QSH) insulators. The (Tl, Rb)/Si(1 1 1) atomic-layer compound synthesized in the present work is the first real system of such type, where atoms of heavy metal Tl are arranged into the honeycomb structure stabilized by Rb atoms occupying the centers of the honeycomb units. Electronic properties of the (Tl, Rb)/Si(1 1 1) compound has been fully characterized experimentally and theoretically and compared with those of the hypothetical (Tl, H)/Si(1 1 1) prototype system. It is concluded that the QSH-insulator properties of the Tl-honeycomb layers on Si(1 1 1) surface are dictated by the stable adsorption sites occupied by Tl atoms which, in turn, are controlled by the atom species centering the Tl honeycombs. As a result, the real (Tl, Rb)/Si(1 1 1) compound where Tl atoms occupy the T4 sites does not possess QSH-insulator properties in contrast to the hypothetical (Tl, H)/Si(1 1 1) system where Tl atoms reside in the T1 (on-top) sites and it shows up as a QSH material

Electronic properties of the two-dimensional (Tl, Rb)/Si(1 1 1)√3x√3 compound having a honeycomb-like structure

Heavy metal layers having a honeycomb structure on the Si(1 1 1) surface were theoretically predicted to show prospects for possessing properties of the quantum spin Hall (QSH) insulators. The (Tl, Rb)/Si(1 1 1) atomic-layer compound synthesized in the present work is the first real system of such type, where atoms of heavy metal Tl are arranged into the honeycomb structure stabilized by Rb atoms occupying the centers of the honeycomb units. Electronic properties of the (Tl, Rb)/Si(1 1 1) compound has been fully characterized experimentally and theoretically and compared with those of the hypothetical (Tl, H)/Si(1 1 1) prototype system. It is concluded that the QSH-insulator properties of the Tl-honeycomb layers on Si(1 1 1) surface are dictated by the stable adsorption sites occupied by Tl atoms which, in turn, are controlled by the atom species centering the Tl honeycombs. As a result, the real (Tl, Rb)/Si(1 1 1) compound where Tl atoms occupy the T4 sites does not possess QSH-insulator properties in contrast to the hypothetical (Tl, H)/Si(1 1 1) system where Tl atoms reside in the T1 (on-top) sites and it shows up as a QSH material

C60 capping of metallic 2D Tl-Au compound with preservation of its basic properties at the buried interface

So-called metal-induced silicon reconstructions (i.e., metal films of monolayer or submonolayer thickness epitaxially grown on single-crystal silicon substrates in ultra-high vacuum) represent a specific class of low-dimensional advanced materials with potential prospects for electronic and spintronic applications. However, they are highly vulnerable to air and, thus, require protective capping. Finding a suitable material is a challenging task, since, in general, the metal-induced reconstructions are vulnerable also to overgrowth of solid layers. In the present study, we have found that C60 fullerite film shows up as a proper capping layer for the (Tl, Au)/Si(1 1 1) 7 х 7 compound reconstruction. Due to a perfect non-distractive epitaxial C60 overgrowth, the metallic Tl-Au compound preserves at the deeply buried interface its atomic structure and all basic electronic properties, including spin-splitting of surface-state bands and conductivity of metallic type with a weak antilocalization effect