A New Surface and Structure for Silicene: Polygonal Silicene Formation on the Al(111) Surface

Seeking a new substrate for fabrication of silicene is of high importance, since its formation in experiment is extremely difficult and only a few substrates have been found to be suitable so far. Reporting of other possible substrates for silicene, particularly cheaper alternatives, would also open up the possibility of controlled experimental growth and functionalization of this new nanomaterial. Here, we show, based on first-principles molecular dynamics calculations, that the honeycomb silicene monolayer is stable on the 4 x 4 Al(111) surface and that it possesses a binding energy comparable to that on the 4 x 4 Ag(111) surface. It is furthermore demonstrated that a new ordered silicene monolayer structure consisting of 3-, 4-, 5-, and 6-sided polygons can also be formed on the Al(111) surface. This new silicene monolayer, which we call polygonal silicene, possesses an almost flat monolayer structure and exhibits a free electron-like density of state, indicating high electronic conduction. The present findings indicate that silicene can take monolayer forms other than the honeycomb lattice as a result of varying the substrate. Silicene is thus expected to exhibit variable electronic properties, which would extend its applicability to possible future nanoelectronics.