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

Abstract

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 (VTH) of ∼5.7 V with field-effect mobility (μFE) 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 (VTH ∼ −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 VTH shift.

Defect-Free Copolymer Gate Dielectrics for Gating MoS2 Transistors

“…The preparation of various high- k metal oxides by atomic layer deposition, such as Al 2 O 3 and HfO 2 , has been reported. − However, the brittle nature of these materials has impeded their use in flexible devices. − Alternatively, polymeric gate dielectrics are good candidates for 2D-material FETs owing to their simple solution processability at room temperature and their good film-forming characteristics, which are compatible with flexible substrates. The use of several polymeric materials such as poly­(4-vinylphenol) and CYTOP fluoropolymer for gating 2D TMDC transistors has been reported. − However, it is difficult to scale down the film thickness (for achieving high capacitance and resulting low-voltage FET operation) without the formation of defects or pinholes by using conventional solution deposition methods. Furthermore, the residual solvent or additives might also degrade the film quality.…”

Flexible and Wavelength-Selective MoS2 Phototransistors with Monolithically Integrated Transmission Color Filters

“…As shown in the inset of Fig. 3a, output current did not saturate within the bias conditions, and exhibited good linearity at low V DS bias indicating Ohmic-like contact behavior between MoS 2 and Au electrode4142.…”

Progress of Large‐Scale Synthesis and Electronic Device Application of Two‐Dimensional Transition Metal Dichalcogenides

“…On the other hand, if the remote CI is arrayed continuously and conformably, the carrier density can be enhanced by a strong doping effect without encumbering mobility. It has already been demonstrated that inserting a polar molecule layer (PMMA, CYTOP, PVP) can modify carrier density and threshold voltage without lowering mobility …”