High-Performance and Scalable Ferroelectric Diodes Enabled via 2D-MoS₂ Buffer Layer Under Low Thermal Budget

Area of Science:

• Materials Science
• Solid State Physics
• Electrical Engineering

Background:

• Hafnium-based (Hf_0.5Zr_0.5O₂, HZO) ferroelectrics offer robust polarization switching for non-volatile memory but suffer from low ON/OFF ratios, high leakage, and poor endurance.
• Atomic Layer Deposition (ALD) compatibility makes HZO suitable for ultrathin films in two-terminal (2-T) memory devices.

Purpose of the Study:

• To develop a high-performance ferroelectric diode (FE-diode) for back-end-of-line (BEOL) compatible memory applications.
• To overcome the limitations of HZO ferroelectrics by optimizing film thickness and incorporating a 2D MoS₂ buffer layer.

Main Methods:

• Fabrication of a W/MoS₂/HZO/TiN stack FE-diode below 400 °C.
• Optimization of HZO thickness (3-8 nm) to shift conduction mechanism from direct tunneling to Schottky emission.
• Synthesis of a 2D MoS₂ buffer layer via low-temperature plasma-enhanced CVD (<300 °C).

Main Results:

• Achieved a high current density of 50 A cm^-2 (at 3 V) and an electroresistance ratio exceeding 2 × 10⁶.
• Demonstrated endurance over 10¹⁰ cycles and stable memory retention for 10 years at room temperature.
• Successfully fabricated a 1K (32 × 32) memory array, confirming device scalability.

Conclusions:

• The W/MoS₂/HZO/TiN FE-diode design significantly enhances performance and stability for non-volatile memory.
• The integration of MoS₂ minimizes interfacial defects, improving device reliability.
• This FE-diode shows strong potential for next-generation integrated memory applications due to its high performance and BEOL compatibility.