Ordered structure upon deposition of Ge on the monolayer silicene on Ag(111)

The growth of monolayer silicene on Ag (111) has been a hot research in recent years. The akin structure of the same group IV element: Germanene, has also been grown successfully on different metal substrates. In this investigation, Ge has been deposited by molecular beam epitaxy on the monolayer-thick silicene grown on Ag(111). Low-temperature scanning tunneling microscopy ( LT-STM ) has been employed to observed the surface morphology and atomic structure. On the ( 3 x 3 )Si phase, only one Ge adatom is found on each ( 3 x 3 )Si unit cell on two different sites, A and B. The deposited Ge adatoms prefer to settle around a unit cell that has already incorporated one Ge adatom, thereby forming two domains ( 3 x 3 )A and ( 3 x 3 )B. Results on ( r7 x r7 )Si superstructure showing local ordering will also be presented.