Thickness-Insensitive Properties of α-MoO₃ Nanosheets by Weak Interlayer Coupling

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Van der Waals (vdW) materials exhibit thickness-dependent properties due to strong interlayer interactions.
• Electrical and tribological properties of vdW oxides and their thickness-insensitivity are understudied.
• Fabrication of high-quality 2D oxides and nanoscale property investigation pose challenges.

Purpose of the Study:

• To investigate the tribological and electrical properties of single-crystal α-MoO3 nanosheets.
• To determine the influence of thickness on friction, adhesion, work function, tunnel current, and dielectric constant.
• To assess the potential of α-MoO3 nanosheets for nanodevice applications.

Main Methods:

• Atomic force microscopy (AFM) was used to study friction and adhesion.
• Conductive AFM was employed for tunnel current measurements.
• Epitaxial growth of α-MoO3 nanosheets on graphite was performed.

Main Results:

• Friction of α-MoO3 nanosheets saturated within a few layers, indicating thickness insensitivity.
• Work function and dielectric constant also showed thickness insensitivity, attributed to weak interlayer coupling.
• Even 2-layer α-MoO3 (1.4 nm) exhibited high dielectric strength (14 MV/cm) and resistance to tunneling.

Conclusions:

• Weak interlayer coupling in α-MoO3 nanosheets leads to thickness-indifferent tribological and electrical properties.
• High crystallinity and weak interlayer interactions are key to these properties.
• α-MoO3 nanosheets show significant potential for advanced nanodevice applications.