OxideLayer kelvin probe force microscopy piezoelectric force microscopy Aluminum WS2 Yeditepe EFM conductive Led Piezo SurfaceChange EFMAmplitude thermal_property Semiconductor Polytetrafluoroethylene Magnets DentalProsthesis HBN mechanical_property FM_KPFM Boundary Film tip_bias_mode LiquidCrystal MoS2 flakes ScratchMode ThermalConductivity Phenanthrene SetpointMode AtomicLayer Sidewall CompactDisk BloodCell Graphite