Structure of silicene on a Ag(111) surface studied by reflection high-energy positron diffraction

Abstract

The structure of silicene fabricated on a Ag(111) surface was determined using reflection high-energy positron diffraction with a linac-based brightness-enhanced intense positron beam. From the rocking curve analysis, the silicene was verified to have a buckled structure with a spacing of 0.83Å between the top and the bottom Si layers. The distance between the bottom Si layer in the silicene and the first Ag layer was determined to be 2.14Å. These results agree with the theoretically predicted values from a previous study [Phys. Rev. Lett. 108, 155501 (2012)] within an error of ±0.05Å.

Emergent elemental two-dimensional materials beyond graphene

“…Remarkably, reflection high energy positron diffraction experiments gave the same atomic geometry of the 33 reconstructed silicene as the one derived from the DFT-GGA calculations [79], which was further confirmed in a dynamic low-energy electron diffraction (LEED) study [80]. Another 2D phase, formed at a slightly higher temperature with, again, no direct evidence of a honeycomb arrangement of the Si atoms in STM or AFM images, was understood in a similar fashion.…”

Silicene: silicon conquers the 2D world

“…Within the 3×3 silicene lattice the Si-Si bond lengths are close to those calculated for free-standing silicene (0.225 nm [9]) but the buckling is nearly doubled, increasing from 0.044 nm to 0.083 nm. This is nicely confirmed by dynamic LEED measurements and, strikingly, reflection high-energy positron diffraction experiments performed in Tsukuba (Japan) [10].…”

Structure Analysis of Two-Dimensional Atomic Sheets by Total-Reflection High-Energy Positron Diffraction

“…The 3 × 3 structure of germanene was fabricated on an Al(111) single crystal surface. The details of the sample preparations were described elsewhere [13][14][15].…”

“…4(a)] [6,7], there was no experimental verification. We then determined the atomic configuration of the silicene on a Ag(111) single crystal thin film grown on a Si(111)-7 × 7 surface [14]. Figure 4(b) shows the rocking curves measured from a 1 × 1 structure of Ag(111) thin film surface and a 4 × 4 structure of silicene on its surface.…”

“…In 2014, germanene also fabricated on Au(111) [9] and Pt(111) substrates [10], and subsequently on Al(111) [11] and MoS 2 substrates [12]. In this review, we reports the recent results on the structure determination of 2D atomic sheets, graphene [13], silicene [14], and germanene [15], on the particular substrates by using total-reflection high-energy positron diffraction (TRHEPD) technique.…”