Giant tunnelling electroresistance in atomic-scale ferroelectric tunnel junctions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Ferroelectric tunnel junctions (FTJs) offer potential for high-reliability, low-power non-volatile memory.
• Scaling FTJs to the atomic level is challenging due to ferroelectric instability and depolarization fields, limiting tunnelling electroresistance (TER).

Purpose of the Study:

• To engineer FTJs capable of maintaining high TER at nanoscale thicknesses.
• To explore novel materials for overcoming limitations in atomic-scale FTJs.

Main Methods:

• Fabrication of FTJs using samarium-substituted layered bismuth oxide.
• Characterization of device performance, including TER, resistance states, endurance, linearity, and retention.

Main Results:

• Achieved a TER of 7 × 10^5 with a 1 nm samarium-substituted bismuth oxide film, three orders of magnitude higher than previous reports.
• Demonstrated up to 32 resistance states without write-verify, high endurance (>5 × 10^9), and long retention (10 years).
• Reported TER > 10^9 for 4.6 nm films, exceeding commercial flash memory performance.

Conclusions:

• Samarium-substituted layered bismuth oxide enables robust FTJs with exceptional TER at the nanoscale.
• These FTJs show significant promise for developing advanced multi-level and reliable non-volatile memory technologies.