Impact of Interface and Surface Oxide Defects on WS₂ Electronic Properties from First Principles

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Industrial-scale dielectric growth on 2D materials for transistors faces performance degradation challenges.
• Maintaining the transport characteristics of 2D material channels during dielectric integration is crucial for device functionality.

Purpose of the Study:

• Investigate the fundamental origins of performance degradation in 2D material transistors.
• Analyze interface properties between tungsten disulfide (WS₂) monolayers and amorphous aluminum oxide (Al₂O₃) or hafnium oxide (HfO₂) thin films.

Main Methods:

• Construction of atomistic interface models between WS₂ and dielectric materials.
• First-principles calculations to compute material properties and interface characteristics.
• Analysis of defect states and surface topology effects on charge carrier transport.

Main Results:

• Achievable van der Waals interfaces between WS₂ and dielectrics are sensitive to surface defects.
• Undercoordinated metal atoms at the surface create detrimental localized states near the WS₂ conduction band edge.
• Surface inhomogeneity, even without defects, leads to non-uniform potentials affecting charge carriers in WS₂.

Conclusions:

• Surface defects and topological inhomogeneity are key bottlenecks limiting WS₂ performance in transistor channels.
• While defects can be managed with material selection, surface inhomogeneity remains a significant challenge for all 2D materials.
• Strategies to mitigate surface inhomogeneity are essential for advancing 2D material-based electronics.