Fig. 3: Characterization of large-area bilayer MoS2 film.

a Photograph of a synthesized bilayer MoS2 film on SiO2/Si substrate (blue) comparison with a bare SiO2/Si substrate (purple), indicating the color changes for before and after MoS2 growth. b Plan-view and c cross-sectional TEM images of the bilayer MoS2 film. The inset of b is a FFT pattern corresponding to the TEM image. d Raman and e PL spectrum of the bilayer MoS2 film. f, g Raman mapping images of the intensity of E12g and A1g modes centered at 383 and 404 cm−1, respectively. h, i XPS spectra of Mo 3d and S 2p core levels of the bilayer MoS2 film, respectively. j Secondary cut-off and k valence band spectra obtained by UPS analysis of bilayer MoS2 film.