Nanoscale friction on MoS₂/graphene heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Stacked 2D materials offer tunable electronic and mechanical properties.
• Molybdenum disulfide (MoS2) and graphene are key 2D materials with unique characteristics.
• Understanding interfacial properties is crucial for designing novel electronic devices.

Purpose of the Study:

• To investigate the structural, work function, and frictional properties of few-layer MoS2 on epitaxial graphene.
• To elucidate the mechanisms governing friction in MoS2/graphene heterostructures.
• To determine the influence of layer number, load, and bias voltage on friction.

Main Methods:

• Chemical vapor deposition (CVD) for growing MoS2 layers on graphene/SiC.
• Atomic force microscopy (AFM) in ultra-high vacuum (UHV) for friction and topography measurements.
• Analysis of load and bias voltage dependence of friction.

Main Results:

• Friction is primarily governed by adhesion and layer deformation.
• Friction decreases with an increasing number of MoS2 layers (1-4 layers).
• Friction dependence on load and bias voltage is linked to interface atomic potential corrugation.

Conclusions:

• Bending rigidity of MoS2 layers reduces deformation and thus friction.
• Interface corrugation, enhanced by load and bias, influences friction.
• Optimizing work function matching minimizes friction in these heterostructures.