PhD thesis of: Hugo CASADEMONT
Contacts: Bruno JOUSSELME & Vincent DERYCKE

MoS₂ Transistors with Ultrathin and Robust Organic Gate Dielectric

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 MoS₂-FETs gate stacks. The devices display excellent switching behavior for reduced gate bias swing (down to 1V) and suppressed hysteresis thank 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.

We are presently extending this study to CVD-based monolayer MoS₂ and to flexible devices.

Référence :

[1] Electrografted Fluorinated Organic Ultrathin Film as Efficient Gate Dielectric in MoS₂ Transistors
H. Casademont, L. Fillaud, X. Lefevre, B. Jousselme, V. Derycke, J. Phys. Chem. C (2016), in press - link