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.