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Aluminium Scandium Nitride Films
Context:
In a recent study, researchers from the Tokyo Institute of Technology (Tokyo Tech) discovered that aluminium scandium nitride (AlScN) ferroelectric films remain stable and maintain their properties at temperatures up to 600°C.
This stability makes them highly promising for next-generation ferroelectric memory devices.
Ferroelectric Materials for Next-Generation Memory
- They have the potential to store gigabytes of data in thin films, ideal for storing movies, video games, and videos.
- These materials have unique ion arrangements that allow two stable polarisation states, similar to 0 and 1 in binary code, for digital data storage.
- Advantages:
- Non-volatile: They retain data without power.
- Efficient Switching: They use a small electric field for fast data writing and reading, leading to low energy consumption.
- Challenges: Existing materials like Pb(Zr,Ti)O3 (PZT) and SrBi2Ta2O9, degrade during high-temperature fabrication with hydrogen.
Key Highlights:
- AlScN films maintain high stability of ferroelectric properties after heat treatment in an H₂-included atmosphere, regardless of electrode material.
- Two crucial factors for ferroelectric materials used in memory devices are remnant polarisation (Pr) and coercive field (Ec).
- Pr signifies the amount of polarisation retained after the electric field is removed, while Ec represents the electric field required to switch the material’s polarisation state.
- High Remanent Polarisation: A higher Pr (>100 µC/cm²) compared to PZT (30–50 µC/cm²), indicating a stronger ability to retain data.
- Stable Coercive Field: Ec of AlScN films increased only slightly (by about 9%) after heat treatment. This small change suggests minimal impact on the energy required for data switching.
- Superior Stability: Unlike other materials, its strong aluminium-nitrogen bond prevents hydrogen from entering the film, preserving stability during fabrication with hydrogen.
- With these characteristics, AlScN films are a strong candidate for next-gen ferroelectric memory devices.
Working Principle
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