FM_SKPM Force-distance Oxidation conductive suspended_graphene pinpoint mode ChemicalCompound Lattice PMNPT Wafer Cell EFM atomic_steps FM-KPFM Laser Optoelectonics Pores PVAP3HT Materials Heat Liquid CP-AFM Sulfur Ceramics BariumTitanate Led Semiconductor PUR light_emission solar_cell thermoplastic_elastomers AtomicSteps graphene_hybrid Sapphire Vacuum