Molecular Approach to Electrochemically Switchable Monolayer MoS₂ Transistors

Abstract As Moore's law is running to its physical limit, tomorrow's electronic systems can be leveraged to a higher value by integrating “More than Moore” technologies into CMOS digital circuits. The hybrid heterostructure composed of two‐dimensional (2D) semiconductors and molecular materials represents a powerful strategy to confer new properties to the former components, realize stimuli‐responsive functional devices, and enable diversification in “More than Moore” technologies. Here, an ionic liquid (IL) gated 2D MoS₂ field‐effect transistor (FET) with molecular functionalization is fabricated. The suitably designed ferrocene‐substituted alkanethiol molecules not only improve the FET performance, but also show reversible electrochemical switching on the surface of MoS₂. Field‐effect mobility of monolayer MoS₂ reaches values as high as ≈116 cm² V⁻¹ s⁻¹ with I_on/I_off ratio exceeding 10⁵. Molecules in their neutral or charged state impose distinct doping effect, efficiently tuning the electron density in monolayer MoS₂. It is noteworthy that the joint doping effect from IL and switchable molecules results in the steep subthreshold swing of MoS₂ FET in the backward sweep. These results demonstrate that the device architecture represents an unprecedented and powerful strategy to fabricate switchable 2D FET with a chemically programmed electrochemical signal as a remote control, paving the road toward novel functional devices.