Defects Scanning_Thermal_Microscopy Hole Photovoltaics atomic_layer ScanningKelvinProbeMicroscopy food StainlessSteel Jason MembraneFilter Conduct Piranha tip_bias_mode Deposition Step nanomechanical Floppy CuSubstrate Litho Al2O3 2d_materials FloppyDisk Hexacontane Piezoresponse doped Sapphire Self-assembledMonolayer CalciumHydroxyapatite Conductive AFM Polyvinylidene Silicon BismuthVanadate Composition WS2 nanobar