Worcester_Polytechnic_Institute ScanningTunnelingMicroscopy temperature_control Ito Sidewall GalliumPhosphide Silicon TemperatureControllerAFM ito_film FM-KPFM SRAM Sio2 temp KAIST semifluorinated alkane Litho alkanes Conductive AFM Tungsten_disulfide HydroGel Piezo Cobalt chemical_compound Vac CrossSection NtuEee Lattice ForceDistanceSpectroscopy non_contact Steps Ecoli HardDiskMedia CalciumHydroxyapatite Platinum Stiffness