To map the thickness-dependent surface potential or work function of the electrode material, we used Kelvin Probe Force Microscopy (KPFM). The instrument operates in amplitude modulation mode (tapping-non-contact mode), a type of dynamic force mode where a cantilever with a thin electrically conductive coating is driven at its resonance frequency. Using the local contact potential difference value between a conducting atomic force microscopy (AFM) tip and the sample, the surface potential was mapped. Figure shows Mn3O4 membrane topography mapped with homogeneous coating of the sample. The line profile indicates a membrane thickness of ~ 2 and 6 nm (Figure ), which is in range with the AFM studies done on exfoliated flakes (Figure and). An average surface potential of -213 mV was measured, as shown in Figure . As compared to silicon substrate potential, which was +306 mV (Figure ), a potential difference of 519 mV was observed. Figure shows a homogeneous phase angle depicting distribution for the flakes within the range of 44.5° to 48.5°. Through the contact potential map (Figure ), electrical properties of Mn3O4 thin membranes was mapped. for ZnO, Ref. for MoS 2 , Ref. for SnSe and Ref. for WSe2.