PiezoelectricForceMicroscopy Thermoplastic_polyurethane SmallScan kelvin probe force microscopy Sapphire Wafer Wang Cross-section FrictionalForce Steps DiffractiveOpticalElements ConductiveAFM NUSNNI ForceVolumeMapping Anneal YszSubstrate STO OrganicSemiconductor GaP MoS2 graphene_hybrid Electronics I-VSpectroscopy Polyurethane PolymerPatterns PtfeMembrane Modulus ForceVolume block_copolymer Zhi FailureAnlaysis Biology Conducting Boron high_resolution