Fig. 3.

Optical characterization of MoS₂-NSs (nanoscrolls). a Raman spectra of chemical vapor deposition (CVD)-grown MoS₂ monolayers (MoS₂-ML, black line) and MoS₂-NSs (red line) with 532 nm excitation. b Optical image of a typical MoS₂-NS. c Corresponding fluorescence image of the MoS₂-NS in b. The fluorescence image was obtained with an excitation wavelength of 510–560 nm. d PL spectra from MoS₂ monolayer (black line) and MoS₂–NSs (red line) (532 nm excitation). e, f PL spectra response of MoS₂ monolayer (e) and MoS₂-NSs (f) with NH₃ doping for 0 s (black line), 10 s (red line), and 10 min (blue line) (scale bars, 5 μm in b and c)