Growth mode and structures of silicene on the Ag(1Â 1Â 1) surface

Low-temperature scanning tunneling microscopy (LT-STM) and ab initio density functional theory (DFT) calculations have been utilized to explore the growth processes and atomic structure of silicene on the Ag(1 1 1) surface. STM images reveal an etching growth mode in the sub-monolayer range. The results confirm the existence of various overlayer structures reported previously and that the lattice parameters of several overlayer structures at sub-monolayer coverages are close to the corresponding substrate supercells. However, detailed analysis of domain boundaries and Moiré-like superstructure in the STM images strongly suggest that the overlayer structures and the substrate lattices have no coincident relationships. Preliminary results of DFT calculations show that the changes in total energy upon translational displacement of the (3 × 3)Si silicene supercells with respect to the Ag(1 1 1) lattice is within a few tens of meV/Si atom.