flakes fluoroalkane UTEM Topography Conduct BoronNitride ReflexLens FrictionForce kelvin probe force microscopy Anneal Gold OxideLayer domain_switching Pipette Liquid Bismuth Ferroelectric HiVacuum Oxidation HafniumDioxide Sadowski Sulfur Ucl fluorocarbon Subhajjit Cell DNA ScanningKelvinProbeMicroscopy FailureAnlaysis OpticalModulator thermal_conductivity SKKU TipBiasMode Scanning_Thermal_Microscopy dichalcogenide