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

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 0.830.28em0ex 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 2.140.28em0ex. These results agree with the theoretically predicted values from a previous study [Phys. Rev. Lett. 108, 155501 (2012)] within an error of ±0.050.28em0ex.