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

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Negative capacitance field-effect transistors (NCFETs) aim to surpass the Boltzmann limit for steeper subthreshold swings (SS).
• Previous NCFET studies often lacked sufficient data range, robust simulations, or used non-uniform exfoliated materials, questioning their practical efficacy.
• Achieving reliable, scalable NCFETs with 2D materials like MoS2 remains a significant challenge.

Purpose of the Study:

• To develop and validate a highly efficient NCFET using synthetic monolayer MoS2 and a ferroelectric gate stack.
• To demonstrate a substantiated subthermionic SS across a wide current range, addressing prior limitations.
• To confirm the critical role of low contact resistance in 2D NCFET performance.

Main Methods:

• Fabrication of an NCFET employing a synthetic monolayer MoS2 channel and a HfZrO ferroelectric gate dielectric.
• Integration of indium metal contacts to minimize source/drain resistance.
• Device characterization including subthreshold swing (SS) and drain-induced barrier lowering (DIBL) measurements.
• Theoretical device modeling incorporating interface trap density.

Main Results:

• Achieved a subthermionic SS of approximately 55 mV/dec over two decades of drain current.
• Distinct observation of negative DIBL-induced threshold voltage shift, a key NCFET characteristic.
• Demonstrated reliable and reproducible low-voltage operation with synthetic monolayer MoS2, unlike exfoliated flake-based devices.
• Confirmed the necessity of reduced contact resistance for effective 2D NCFET implementation.

Conclusions:

• The synthetic monolayer MoS2 NCFET offers a scalable and reproducible pathway to sub-60 mV/dec SS, overcoming previous limitations.
• Indium contacts are crucial for mitigating contact resistance, enabling high-performance 2D NCFETs.
• This work validates the potential of NCFETs for future low-power electronics through advanced material synthesis and device engineering.