Room-Temperature Ferroelectricity in Ultra-Thin p-Type BiCuSeO Films

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Atomically thin 2D layered ferroelectric semiconductors are crucial for next-generation electronics due to their intrinsic polarization switching capabilities.
• Challenges persist in the controlled synthesis of these materials and the manipulation of their ferroelectric properties.

Purpose of the Study:

• To synthesize ultrathin 2D p-type BiCuSeO (BCSO) films.
• To confirm and characterize the room-temperature ferroelectricity of BCSO films.
• To elucidate the mechanism behind ferroelectricity in BCSO and demonstrate its application in ferroelectric tunnel junctions.

Main Methods:

• Molecular beam epitaxy for film synthesis.
• Piezoelectric force microscopy for ferroelectric characterization.
• Density functional theory calculations and cross-sectional scanning transmission electron microscopy for mechanism investigation.

Main Results:

• Successful synthesis of ≈3 nm thick 2D p-type BCSO films.
• Confirmation of robust room-temperature out-of-plane ferroelectricity and switching capability.
• Identification of polar displacement in [CuSe] layers as the primary ferroelectric mechanism.
• Demonstration of distinct ON and OFF states in BCSO-based ferroelectric tunnel junctions.

Conclusions:

• Ultrathin 2D BCSO films exhibit promising room-temperature ferroelectric properties.
• The identified ferroelectric mechanism provides fundamental insights for material design.
• BCSO is a versatile material for developing future multifunctional electronic devices.