Coexistence of multiple silicene phases in silicon grown on Ag(1 1 1)

Abstract

Silicene, the silicon equivalent of graphene, is attracting increasing scientific and technological attention in view of the exploitation of its exotic electronic properties. This novel material has been theoretically predicted to exist as a free-standing layer in a low-buckled, stable form, and can be synthesized by the deposition of Si on appropriate crystalline substrates. By employing low-energy electron diffraction and microscopy, we have studied the growth of Si on Ag(1 1 1) and observed a rich variety of rotationally non-equivalent silicene structures. Our results highlight a very complex formation diagram, reflecting the coexistence of different and nearly degenerate silicene phases, whose relative abundance can be controlled by varying the Si coverage and growth temperature. At variance with other studies, we find that the formation of single-phase silicene monolayers cannot be achieved on Ag(1 1 1).

Determining the atomic structure of the ( 4×4 ) silicene layer on Ag(111) by combined grazing-incidence x-ray diffraction measurements and first-principles calculations

“…Experimentally, 2D silicon structures have been reported to grow onto different substrates, such as ZrB 2 (0001) [8], Ir(111) [9], and MoS 2 [10]. Nevertheless, most of the studies have been performed on Ag (111) and Ag(110) [5,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Silver appears to be appropri-ate for silicene growth since: (i) the Ag-Si phase diagram shows non-miscibility of the solid phases, (ii) Ag and Si lattice constants are in 3/4 ratio and (iii) their similar electronegativity should result in a small charge transfer between the Si layer and the substrate.…”

Dirac fermions in silicene on Pb(111) surface

“…DFT calculations as well as low energy electron dispersion (LEED) and scanning tunneling microscopy (STM) results indicate several arrangements of silicene that differ slightly in buckling of the layers, coverage and rotation relative to the silver substrate. The superstructures 4Â4, 6 12 Although the atomic structure of silicene on silver is rather well known, its electronic properties are still discussed. The 4Â4 superstructure is most commonly observed and investigated.…”

Experimental and theoretical determination ofσbands on (“23×23”) silicene grown on Ag(111)

“…The formation of the different reconstructions depends on substrate temperature, deposition rate, and coverage. They all form within a small region of parameter space and samples generally exhibit more than one silicene reconstruction [16][17][18][19]. Angle-resolved photoelectron spectroscopy (ARPES) experiments have focused on the (4 × 4) phase since it is aligned with the (1 × 1) unit cell of Ag(111) [4,5,7].…”