Realization of Extremely High-Gain and Low-Power in nMOS Inverter Based on Monolayer WS₂ Transistor Operating in...

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Monolayer transition metal dichalcogenides (TMDs) like WS₂ are promising for next-generation electronics.
• Achieving high-performance n-type field-effect transistors (FETs) in TMDs remains a challenge.
• Large-area synthesis of high-quality TMD materials is crucial for practical applications.

Purpose of the Study:

• To fabricate and characterize n-type metal-oxide-semiconductor (nMOS) inverters using chemical vapor deposition (CVD)-grown monolayer WS₂ FETs.
• To investigate the electrical properties and gain performance of these WS₂ nMOS inverters.
• To explore the potential of monolayer WS₂ for low-power, high-gain logic circuits and integrated systems.

Main Methods:

• Large-area monolayer WS₂ films were synthesized using chemical vapor deposition (CVD).
• n-type doping was achieved using AlOₓ/Al₂O₃, and a double-gate structure with high-κ HfO₂ dielectric was employed.
• Fabrication and electrical characterization of WS₂ FETs and nMOS inverters were performed.

Main Results:

• CVD-grown monolayer WS₂ FETs exhibited excellent electrical properties, including high on/off ratios and small subthreshold swings.
• Subthreshold operating WS₂ nMOS inverters achieved exceptionally high intrinsic gains (564 at 1 V, 2056 at 2 V) and low power consumption (∼2.3 pW·μm⁻¹ at 1 V).
• Demonstrated logic circuits included AND, OR, NAND, NOR gates, and static random-access memory (SRAM), showcasing WS₂'s circuit integration capabilities.

Conclusions:

• Monolayer WS₂ FETs, when properly doped and structured, can form high-gain, low-power nMOS inverters.
• The superior subthreshold characteristics of WS₂ FETs enable significantly higher intrinsic gain than conventional silicon MOSFETs.
• These results highlight the potential of large-area CVD-grown monolayer WS₂ for practical, high-performance logic circuits and integrated systems.