Fig. 5: PiFM-KPFM measurements of extrinsically stacked FLG under triboelectric control.

a Topography and (b). V_CPD map of extrinsically stacked FLG. PiFM images at (c). 1574 cm⁻¹ (off resonance) and (d). 1582 cm⁻¹ (on resonance). The white scale bar is 2 μm. e PiFM spectrum on the PMMA aggregation (red cross in the topography). f Block diagram of pristine regions (blue shaded) and rubbed (red shaded) regions, taking into account the pristine and overlapping area (gray dashed area), denoted as L and (o), respectively. g Work function and (i). Normalized PiFM response of pristine (solid line-squares) and rubbed (dashed line-squares) areas with respect to the number of layers. V_CPD vs PiFM correlation plot at (h). 1574 cm⁻¹ (off resonance) and (j). 1582 cm⁻¹ (on resonance). All the normalizations are conducted by the PiFM signal of substrate (SiO₂)