Fig. 3: Raman spectra analysis of the irradiation effect on monolayer MoS2.

a The Raman spectra of monolayer MoS2 with different radiation doses up to 105 μC/cm2. The peaks for unirradiated sample at ~386 cm−1 (E2g) and 405 cm−1 (A1g) are consistent with previous reports for monolayer MoS2. b E2g peak intensity, (c) A1g peak intensity, and (d) 2LA(M) peak intensity with different radiation doses. A decrease of intensity can be observed as dose increases. The 2LA(M) peak disappears at high radiation doses. These suggest sulfur vacancies are introduced to the MoS2 film after irradiation. The Raman spectra are measured on three different locations for each dose to compensate for variation from material growth.