In-Plane Ferroelectric Domain Wall Memory with Embedded Electrodes on LiNbO₃ Thin Films

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Lithium niobate (LiNbO3) thin films are promising for high-density domain wall memory.
• Traditional fabrication methods involving etching are challenging due to LiNbO3's hardness and inertness, risking ferroelectric damage.
• Etching also limits the ability to create inclined side edges crucial for polarization retention.

Purpose of the Study:

• To develop an etching-free technique for fabricating LiNbO3-based memory cells.
• To overcome poor domain retention and weak wall currents in previous gapped electrode designs.
• To enhance the stability and read-out capabilities of domain wall memory in LiNbO3 thin films.

Main Methods:

• Developed a technique to deposit gapped electrodes directly onto the LiNbO3 film surface, avoiding etching.
• Investigated domain switching via in-plane voltage application, creating conducting domain walls.
• Fabricated embedded electrodes diffusing into the film to screen depolarization fields and explored critical gap distances for domain stabilization.

Main Results:

• Demonstrated reversible domain switching and "on"/"off" current read by creating/erasing conducting domain walls.
• Embedded electrodes significantly improved domain retention and wall current by screening depolarization fields.
• Increasing the gap distance beyond 320 nm also stabilized switched domains without embedded electrodes.

Conclusions:

• Etching-free fabrication of LiNbO3 memory cells is achievable using novel electrode integration.
• Embedded electrodes or optimized gap distances effectively mitigate depolarization fields, enhancing memory performance.
• These advancements pave the way for damage-free, high-density domain wall memory devices based on LiNbO3.