Figure 1

(a) A schematic of our CVD setup for the synthesis of WS₂. (b) An optical microscope image of NaCl-assisted WS₂. (c) Raman and (d) PL spectra of WS₂ grown with NaCl. The dotted lines in (c) correspond to the peak positions of the E′ (356.7 cm⁻¹) and A′₁ (418.2 cm⁻¹) modes in the monolayer region of WS₂. (e) A typical optical image of WS₂ grown in the absence of NaCl. The white dotted lines show the boundary between the scratch and the WS₂ film. In (b–e), the green component was extracted from the original images and the contrast was enhanced for easy visualisation of WS₂.