Growth of Ge and Si on the Monolayer Silicene on Ag(111) and Al(111)
Han-De Chen1, Ko-Hsiang Chien1, Deng-Sung Lin1*
1Dept. of Physics, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Deng-Sung Lin,
Well-ordered monolayer silicene layers can be prepared on both the Ag(111) and Al(111) surfaces. Futher growth of Ge by molecular beam epitaxy on top of silicene monolayer on the Ag(111) surface results in either a dispersed adlayer or a two-dimensional ordered depending on the silicene phases [1]. Scanning tunneling microscopy (STM) images show that the ordered adsorbed Ge atoms on the domains occupy directly on top of down-atoms in the buckled silicene layer. By contrast, further growth Si on the silicene up to several MLs results in an atomic flat film with surface structure. We use low-temperature scanning tunneling microscopy (LT-STM) to observe the chemical response of the film surface exposed to an atomic deuterium (D) beam. We find D displaces the Ag surfactant adatoms, resulting in a D-terminated (1 × 1) surface. The displaced Ag atoms migrate on the surface to form Ag(111) crystallites. The results confirm that the surfaces of the few-layer Si films grown on Ag(111) are Ag terminated and suggest that the films have a diamond-like structure [2]. Differences between the Ag(111) and Al(111) substrate will also be presented.

[1]. Lin, H.-D. C. a. D.-S., Ordered 2d Structure Formed Upon the Mbe Growth of Ge on the Silicene/Ag(111) Surface 2016.
[2] Chen, H.-D.; Chien, K.-H.; Lin, C.-Y.; Chiang, T.-C.; Lin, D.-S., Few-Layer Silicon Films on the Ag(111) Surface. J. Phys. Chem. C 2016, 120, 2698-2702.

Keywords: Silicene, Germanene, low-temperature scanning tunneling microscopy (LT-STM)