Enhancement-mode operation of multilayer MoS₂ transistors with a fluoropolymer gate dielectric layer

Enhancement-mode multilayer molybdenum disulfide (MoS₂) field-effect transistors (FETs), which are an immensely important component toward low-power electronics based on a two-dimensional layered semiconductor, are demonstrated using the fluoropolymer CYTOP as a gate dielectric. The fabricated devices exhibit threshold voltage (V_TH) of ∼5.7 V with field-effect mobility (μ_FE) of up to 82.3 cm²/V s, and the characteristics are compared with the depletion-mode characteristics of MoS₂ FETs with the cross-linked Poly(4-vinylphenol) gate dielectric (V_TH ∼ −7.8 V). UV photoelectron spectroscopy analysis indicates that increased surface potential due to the surface dipole effect of the fluorine group influences the positive V_TH shift.