Figure 2

(a) A typical cross-sectional TEM image of WS₂. The thickness of the WS₂ is ~0.6 nm, which indicates that the WS₂ is a monolayer. Amorphous carbon was deposited when the cross-sectional sample was fabricated. (b) The corresponding EDX spectrum measured at the WS₂ region is marked by a red circle in (a).