Figure 4

(a–d) Comparison of photoemission spectra between the CVD-grown 1L- and 2L-MoS₂ samples before and after low-energy (100 eV) He⁺ ion irradiation. The photoemission data were taken at the photon energy of hν = 360 eV. (e–g) The work functions were measured at three random positions for each sample using an ambient Kelvin probe system.