Figure 1. Synthesis and characterization of monolayer MoS₂.

(a) and (b) Optical images of typical MoS₂ on 280 nm SiO₂/Si substrates synthesized by CVD method. The growth durations are 10 min and 20 min, respectively. In (b), some monolayer MoS₂ islands overlapped with one another because of the longer growth time, as indicated with arrows. The scale bars correspond to 10 μm. (c) AFM image of two neighbored MoS₂ triangular islands. The white curve shows the thickness along the red dashed line. The scale bar corresponds to 0.5 μm. (d) Room-temperature PL spectra from monolayer MoS₂ (red) and bilayer MoS₂ (black). Peak height is normalized to the silicon Raman peak. Raman signals also appear in the PL spectra at the higher energy, details of which are shown in the inset. (e) HRTEM image of freely suspended monolayer MoS₂. The inset is the corresponding SAED pattern recorded along the [001] zone axis. The scale bar corresponds to 2 nm.