KelvinProbeForceMicroscopy HydroGel SiliconCrystal KPFM high_resolution Water SiliconeOxide Polarization Mfm Potential doped LateralPFM thermoplastic_elastomers flakes conductive Conductance Hole Defects EFMAmplitude SurfaceChange Filter CrystalGrowing Chungnam_National_University FrequencyModulation gallium_nitride atomic_steps Bio ScanningIon-ConductanceMicroscopy HighAcpectRatio Regensburg ThermalConductivity ChemicalCompound LiIonBattery Photovoltaics PECurve