High-k 2D Sb₂O₃ Made Using a Substrate-Independent and Low-Temperature Liquid-Metal-Based Process

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• High-dielectric-constant (high-k) ultrathin films are crucial for insulating gate materials in electronics.
• Conventional high-k dielectrics like HfO2 and ZrO2 have limitations in forming distinct ultrathin sheets.
• There is a need for new high-k nanomaterials (k=40-100, band gap > 4 eV) for advanced applications.

Purpose of the Study:

• To synthesize and characterize 2D antimony oxide (Sb2O3) nanosheets as a potential high-k dielectric.
• To evaluate the material's suitability for electronic applications, particularly as a gate oxide.
• To demonstrate a novel, industry-compatible synthesis method for these ultrathin films.

Main Methods:

• Liquid metal synthesis technique using a bismuth-antimony alloy.
• Low-temperature, substrate-independent fabrication process.
• Liquid metal print transfer for depositing ultrathin α-Sb2O3 onto surfaces.

Main Results:

• Successfully synthesized stoichiometric cubic 2D antimony oxide (α-Sb2O3) nanosheets.
• Achieved tunable sheet thickness (1.5-3 nm) with millimeter lateral dimensions.
• Observed high crystallinity, a wide band gap (~4.4 eV), a maximum relative permittivity (k) of 84, and a breakdown electric field of ~10 MV/cm.
• Demonstrated low leakage currents in field-effect transistors utilizing the α-Sb2O3 nanosheets.

Conclusions:

• 2D α-Sb2O3 nanosheets are a promising high-k dielectric material meeting desired specifications.
• The developed liquid metal synthesis technique is compatible with silicon industry standards.
• The material shows potential for use in conventional and van der Waals heterostructure-based electronics.