High-Performance Negative Capacitance Field-Effect Transistors with Synthetic Monolayer MoS₂.

Abstract

Although negative capacitance field-effect transistors (NCFETs) have been extensively studied to overcome the fundamental Boltzmann limit, many prior reports on sub-60 mV/dec subthreshold swings (SS) suffer from inadequate data ranges, measurements near the noise floor, and a lack of robust device simulations, raising questions about the true efficacy of NCFETs. Moreover, recent efforts with MoS₂ channels have frequently relied on mechanically exfoliated flakes, limiting device uniformity and scalability. Here, we present an NCFET that employs a synthetic monolayer MoS₂ channel and a ferroelectric hafnium zirconium oxide layer in the gate stack integrated with indium metal contacts. We achieve a clearly substantiated subthermionic SS (∼55 mV/dec) across more than two decades of drain current, supported by theoretical modeling that incorporates interface trap density. Additionally, the negative drain-induced barrier lowering (DIBL)-induced threshold voltage shift, a hallmark of NCFETs, is distinctly observed. Compared to existing 2D van der Waals (vdW) NCFETs that rely on exfoliated material, our synthetic monolayer MoS₂ approach demonstrates a reliable and reproducible low-voltage operation, underlining its potential for large-area integration. We further confirm that reducing source/drain contact resistance (achieved with indium metal contacts) is vital for the successful implementation of monolayer 2D vdW NCFETs.