Silicene beyond mono-layers--different stacking configurations and their properties.

Area of Science:

• Computational materials science
• Condensed matter physics
• Surface science

Background:

• Silicene, a single layer of silicon atoms, shares graphene-like properties.
• Understanding multi-layer silicene is crucial for novel electronic applications.

Purpose of the Study:

• Investigate geometric and electronic properties of multi-layer silicene (n=1-10).
• Compare multi-layer silicene to multi-layer graphene.
• Analyze the impact of different stacking configurations on stability and electronic band structure.

Main Methods:

• Ab initio density functional theory (DFT) calculations.
• Systematic study of layer-dependent properties.
• Analysis of stacking configurations (AAAA, AABB, ABAB, ABC).

Main Results:

• Strong covalent inter-layer bonding in silicene, contrasting with graphene's van der Waals forces.
• Silicene's electronic band structure (linear/parabolic dispersions) is shifted due to inter-layer bonding.
• Tetrahedral (AAAA, AABB, ABC) stacking configurations are more energetically stable than Bernal (ABAB) stacking.
• Surface states in lower-energy configurations contribute to semi-metallic character.

Conclusions:

• Multi-layer silicene properties are distinct from graphene due to strong covalent bonding.
• Stacking configuration significantly impacts stability and electronic properties.
• Tetrahedral coordination leads to higher cohesive energy and unique surface states, suggesting potential for advanced electronic materials.