Top-Gated MoS₂ Negative-Capacitance Transistors Fabricated by an Integral-Transfer of Pulsed Laser Deposited HfZrO₂ on Mica

Top-gated (TG) molybdenum disulfide (MoS ₂ ) field-effect transistors (FETs) suffer from surface damage, unintentional doping, and other defects introduced to the MoS ₂ channel during the direct deposition of the gate dielectric. In addition, the delicate MoS ₂ cannot withstand high-temperature processing or annealing. To overcome these obstacles, a novel path to prepare TG MoS ₂ negative-capacitance (NC) FETs is proposed in this study. A ferroelectric HfZrO ₂ (HZO) is first deposited on the mica flake by pulsed laser deposition (PLD) and then annealed by rapid thermal processing. Subsequently, the HZO/mica stack is integrally transferred onto the MoS ₂ surface, without needing to expose the MoS ₂ flake to harsh temperatures or PLD environments. TG multilayered MoS ₂ NCFETs with the HZO/mica stack are fabricated and demonstrate stable NC effects and superior performance with a subthreshold swing (SS) of 49 mV/dec, ON/OFF current ratio above 10 ⁷ , and anticlockwise hysteresis voltages of 64 mV, which are attributed to vital contributions from the damage-free mica/MoS ₂ van der Waals heterojunction interface and reasonable capacitance matching between the mica dielectric and the ferroelectric HZO film. Moreover, the experimental results of the dual-gate MoS ₂ transistor modulated by the bottom gate show that a positive bottom-gate bias can increase drain current and decrease hysteresis voltage, and a negative bottom-gate bias can reduce SS. Therefore, the proposed approach changes the current situation that the PLD method is hardly used to fabricate TG MoS ₂ transistors and opens a new window for nanoelectronics.