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The paper shows how Kelvin probe force microscopy (KPFM) and Raman spectroscopy can identify the six polytypes of five-layer graphene. KPFM maps the local surface potential, which depends on interlayer hybridization and thus on stacking order. Each stacking sequence produces a distinct potential contrast relative to monolayer graphene, allowing non-destructive, real-space discrimination of different five-layer stackings and linking them to their electronic properties.​

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These results were achieved through the high spatial and contact potential resolution provided by sideband KPFM measurements performed with the Park NX-Hivac AFM.