Model dielectric function for 2D semiconductors including substrate screening

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Physics

Background:

• Exciton dielectric screening in 2D semiconductors is a complex, non-local phenomenon.
• This non-locality is strongly dependent on momentum transfer (q) in reciprocal space.
• Existing ab initio methods for calculating screening are computationally intensive.

Purpose of the Study:

• To present an analytical dielectric function model that captures the full non-linear q-dependency.
• To offer a computationally efficient alternative to ab initio screening methods.
• To investigate the impact of substrate screening on 2D material properties.

Main Methods:

• Development of an analytical dielectric function model incorporating full q-dependency.
• Validation against ab initio calculations for excitonic optical properties.
• Application to monolayer hexagonal boron nitride (hBN), molybdenum disulfide (MoS2), and reconstructed silicon surfaces.
• Systematic study of substrate effects on MoS2 and hBN excitonic properties.

Main Results:

• The analytical model shows good agreement with ab initio results for excitonic optical properties.
• The model effectively incorporates non-local effects and momentum transfer dependence.
• Substrate screening effects on MoS2 and hBN were systematically studied and quantified.
• The model proved versatile across different 2D materials and surface systems.

Conclusions:

• The developed analytical model provides a versatile and efficient tool for studying dielectric screening in 2D materials.
• It accurately predicts excitonic properties and simplifies the inclusion of substrate effects.
• This approach offers a valuable alternative to computationally demanding ab initio methods for condensed matter research.