General Approach for Two-Dimensional Rare-Earth Oxyhalides with High Gate Dielectric Performance

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Chemistry

Background:

• Two-dimensional (2D) rare-earth oxyhalides (REOXs) possess unique properties for advanced applications.
• Fabricating 2D REOXs and heterostructures is essential for exploring their potential but remains challenging.
• A general, facile method for 2D REOX synthesis is needed.

Purpose of the Study:

• To develop a general strategy for synthesizing 2D rare-earth oxyhalide (REOX) nanoflakes.
• To investigate the growth mechanism of these 2D materials.
• To demonstrate the application of 2D REOXs in high-performance electronic devices.

Main Methods:

• Molten salt synthesis assisted by a substrate.
• Characterization of synthesized 2D LnOCl (Lanthanide Oxychloride) nanoflakes.
• Fabrication and testing of MoS2 field-effect transistors utilizing LaOCl as a gate dielectric.

Main Results:

• Successfully prepared 2D LnOCl nanoflakes (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) using a facile molten salt method.
• Proposed a dual-driving mechanism for lateral growth involving the quasi-layered structure and substrate interaction.
• Demonstrated epitaxial growth of lateral heterostructures and superlattices.
• Achieved high-performance MoS2 transistors with LaOCl gate dielectric, showing on/off ratios up to 10^7 and subthreshold swings of 77.1 mV dec^-1.

Conclusions:

• The developed molten salt strategy provides a general approach for synthesizing various 2D REOX nanoflakes and heterostructures.
• The findings offer a deeper understanding of 2D REOX growth mechanisms.
• This work highlights the significant potential of 2D REOXs in future electronic devices.