Bi₂O₂Se-Based Monolithic Floating-Gate Nonvolatile Memory with Enhanced Charge Retention and Switching Performance

Area of Science:

• Materials Science
• Solid-State Electronics
• Nanotechnology

Background:

• Conventional floating-gate memories face scaling limitations due to charge leakage and complex structures.
• Existing 2D nonvolatile memory (NVM) devices often require multiple material layers for different functions.

Purpose of the Study:

• To develop a monolithic NVM device using a single 2D material.
• To integrate channel, charge storage, and tunneling functionalities within one material system.
• To overcome the fabrication complexity and scalability issues of current 2D NVMs.

Main Methods:

• Utilized a single 2D material, Bi2O2Se, for device construction.
• Employed UV-ozone treatment to form a crystalline oxide shell (β-Bi2SeO5).
• Introduced selenium vacancies via thermal annealing to create a metallic core (m-BOS) for charge storage.

Main Results:

• Achieved a monolithic NVM device integrating channel (s-BOS), storage (m-BOS), and tunneling (BOS oxide) functions.
• Demonstrated a large memory window, high storage density (~5 × 10^13 cm^-2), and ON/OFF ratio > 10^8.
• Exhibited fast programming/erasing (±12 V, 100 ms), endurance (>2000 cycles), and retention (>10^4 s).

Conclusions:

• The single-material Bi2O2Se platform simplifies fabrication and enhances scalability for 2D NVM devices.
• This approach offers a promising alternative to multilayered memory architectures.
• The device performance metrics meet requirements for advanced memory applications.