Figure 1
From: Effects of Oxygen Adsorption on the Surface State of Epitaxial Silicene on Ag(111)
Topographical images of Ag(111) substrate and 4 × 4 silicene grown on Ag(111).
(a) STM topographical image of clean Ag(111) substrate, which shows a clear quantum-interference pattern due to point defects (scanning area 15 nm × 15 nm, Vbias = −0.2 V, I = 4 nA). (b) STM topographical image of 4 × 4 silicene on Ag(111) (scanning area 15 nm × 15 nm, Vbias = −0.8 V, I = 2 nA). Inset is an enlarged view of an area 4 nm × 4 nm in size. (c) STM image of silicene layer oxidized by an oxygen dose of 10 L. O adatoms prefer to reside at bridge sites. The inset contains STS spectra of silicene and silicene oxide samples, indicating that there is gap opening due to oxidation. (d) STM image of the 4 × 4 silicene oxidized under 600 L O2. The bare Ag(111) surface can be seen at the bottom left of (d).
