Electrografted Fluorinated Organic Ultrathin Film as Efficient Gate Dielectric in MoS 2 Transistors

Abstract : Dielectric films with nanometer thickness play a central role in the performances of field effect transistors (FETs). In this article, a new class of organic gate dielectric based on the electrochemical grafting of diazonium salts on metallic electrodes is investigated. The versatile diazonium salt strategy is a local and room-temperature process that provides robustness and performances. Moreover, this process produces ultrathin (4−8 nm) and smooth films. To prove their efficiency as gate dielectric, they were integrated in MoS 2 −FETs gate stacks. The devices display excellent switching behavior for reduced gate bias swing (down to 1 V) and suppressed hysteresis thanks to the highly hydrophobic nature of the fluorinated grafted film. Furthermore, the devices exhibit steep subthreshold slopes (as low as 110 mV/decade), demonstrating excellent gate coupling.