Figure 5.

(a) Representative Raman spectra of the few-layers (FL) MoS₂ (black-line) and multilayer (ML) MoS₂ samples obtained by sulfurization of the 2.8 and 4.2 nm MoO₃ films on SiO₂. Colour maps of the A_1g-E_2g wavenumber difference Δω obtained from arrays of Raman spectra collected on 10 μm × 10 μm scan areas on the FL-MoS₂ (b) and on the ML-MoS₂ (c) samples. Histogram of Δω values showing a distribution with a peak at ω ≈ 21.8 ± 0.6 cm⁻¹ for the FL-MoS₂ sample associated to 2 L–3 L MoS₂ (d) and ω ≈ 24.8 ± 0.4 cm⁻¹ for the ML-MoS₂ sample, corresponding to >4 L MoS₂ thickness (e).