Fig. 2: LEFM measurement on MoS₂ sample.

a The representative vibration amplitude vs. the external bias curves on monolayer MoS₂ under the regular EFM working mode. The inset is the zoom-in of the apex area. The offset of the parabolic curve from the zero bias indicates \({V}_{{{{{{\rm{CPD}}}}}}}\). The representative curves of vibration amplitude vs. external bias on b monolayer, d bilayer, and e multilayer (thickness ∼22 nm) MoS₂ with the LEFM working mode. The bias ranges corresponding to the valance band, band gap, and conduction band of the samples are shaded in blue, red, and green respectively and the band edges are marked by the red dashed lines. c The optical image of the few-layer MoS₂ samples on an ITO substrate. The insets present the corresponding AFM topography mapping and the height profile along the red dashed line (scale bars: 5 μm).