Silicene structures on silver surfaces

Abstract

In this paper we report on several structures of silicene, the analog of graphene for silicon, on the silver surface Ag(100), Ag(110) and Ag(111). Deposition of Si produces honeycomb structures on these surfaces. In particular, we present an extensive theoretical study of silicene on Ag(111) for which several recent experimental studies were published. Different silicene structures were obtained only by varying the silicon coverage and/or its atomic arrangement.All the studied structures show that silicene is buckled with a Si-Si nearest neighbor distance varying between 2.28 Å and 2.5Å. Due to the buckling in the silicene sheet, the apparent (lateral) Si-Si distance can be as low as 1.89 Å. We also found that for a given coverage and symmetry, one may observe different STM images corresponding to structures that differ by only a translation.

Combined AFM and STM measurements of a silicene sheet grown on the Ag(111) surface

“…For the (4x4) superstructure of silicene on Ag(111), the nc-AFM measurements clearly indicate a strong buckling of the Si honeycomb layer. [8,16] matches very well our data.…”

“…The atomic contrast acquired by nc-AFM and STM consists of 6 characteristic protrusions arranged in 2 triangles within the unit cell. The observation coincides very well with the proposed (4x4) model structure 8,16 as can be seen directly in Fig.1d. In particular, the (4x4) model structure shows clearly that the Si atoms are relaxed out of the surface plane forming pyramids, whose apices are located at the positions where both the STM and AFM show bright protrusions.…”

“…[3][4][5][6] Experimentally, we have succeed in synthesizing silicene on both the Ag(110) and Ag (111) substrates. [7][8][9][10] On the Ag(110) surface, massively parallel silicene nano-ribbons (NRs) of 1.6 nm wide were obtained. 7,10 We have shown that their reactivity towards molecular oxygen is substantially less than that of silicon.…”

Thermoelectric properties of atomically thin silicene and germanene nanostructures

“…In particular, it is viewed as a new type of atomic-layered material with outstanding properties such as the zero effective mass at the Dirac point and infrared absorbance optical spectra [22][23][24]. Experimentally, single layer silicene (buckled) [25][26][27][28][29][30][31][32][33][34][35][36] and silicene nanoribbons (SiNRs) [25,27] have been synthesized on Ag substrate. In particular, SiNRs up to a narrow width of 1.6 nm have been produced, aligned parallel to each other in a well-distributed way [25].…”

Silicene beyond mono-layers—different stacking configurations and their properties

“…On the other hand, inducing a band gap by applying an electric field is not possible in monolayer of graphene. It is interesting to note that, recently, silicene has been grown epitaxially on a close-packed silver surface [20][21][22][23][24][25][26] and hence it opens up a possibility of validating the existing theoretical prediction.…”