Surface enhanced Raman effect on CVD growth of WS2 film

Highlights: • Large area WS₂ flakes are prepared via chemical vapor deposition (CVD) method. • The as-grown WS₂ films are demonstrated to be excellent as substrates for SERS. • The Raman enhancement effect depends crucially on the layer number of WS₂ film. Chemical vapor deposition (CVD) method was used to grow large area and layer controllable WS₂ film. Our results show that the as grown WS₂ film is an excellent substrate for surface enhanced Raman scattering (SERS). The Raman enhancement effect depends crucially on the layer number of WS₂ film: monolayer WS₂ offers the strongest Raman signal, and the Raman enhancement effect gradually decreases with the increase in the layer number of WS₂. Further analysis indicates that this transition originates from the charge transfer yield between the R6G molecules and the underlying WS₂ substrate.