Fig. 1. The SKPM experimental results of few-layer MoS₂ （a） the AFM image of stepped MoS₂，including 1L，2L，3L ，4L and 6L，（b） the SKPM image of the corresponding topography of MoS₂，（c） the MoS₂ height profile corresponding to the white dashed line marked in （a），（d） the surface potential distribution of few-layer MoS₂ extracted from （b），（e） the bandgap and potential of MoS₂ as a function of layer thickness，in black and red，respectively （the bandgap data are from the theoretical calculation results in Ref. 5），the potential data at 6L are regional average，（f） evolution of the Fermi level of MoS₂ with different layers

Fig. 2. The SKPM experimental results of few-layer MoTe₂ （a） the AFM image of stepped MoTe₂，including 1L，2L and 3L，（b） the SKPM image of the corresponding topography of MoTe₂，the light blue dashed lines are extensions of the potential boundary，The white triangles in white dashed ovals mark topography and potentials due to the module absorption or contamination，（c） the surface potential distribution and corresponding topography of the few-layer MoTe₂ extracted from （a） and （b），（d） the height and potential curves corresponding to the white dotted line in the MoTe₂ monolayer region in （b），（e） evolution of the Fermi level of MoTe₂ with different layers，（f） the number and average potential of adsorbates with different diameter ranges in the monolayer region of MoTe₂

Fig. 3. The SKPM experimental results of MoTe₂/MoS₂ vdW heterostructures （a） the AFM 3D image of MoTe₂/MoS₂ vdW heterostructure，（b） the SKPM 3D image of corresponding topography，（c） the topography and surface potential distributions corresponding to the white dashed line in （b），（d） the size dependence of the potential difference between the MoTe₂/MoS₂ vdW heterojunction and MoS₂ under dark and light conditions，the inset shows the changes in surface potential of the MoTe₂/MoS₂ heterostructure under dark and light conditions