First principles study and empirical parametrization of twisted bilayer MoS2 based on band-unfolding

TL;DR

This paper combines first principles calculations and empirical modeling to analyze the electronic band structure and transport properties of twisted bilayer MoS2, providing a new approach for understanding its electronic behavior.

Contribution

It introduces an efficient two-band effective mass model for twisted bilayer MoS2 based on band-unfolding from DFT calculations, enabling better transport property predictions.

Findings

Unfolded band structures reveal twist angle dependent band edges.

The two-band model accurately fits the DFT band structures.

Ballistic transmission varies with twist angle and can be predicted using the model.

Abstract

We explore the band structure and ballistic electron transport in twisted bilayer $\textrm{MoS}_2$ using Density Functional Theory (DFT). The sphagetti like bands are unfolded to generate band structures in the primitive unit cell of the original un-twisted $\textrm{MoS}_2$ bilayer and projected onto an individual layer. The corresponding twist angle dependent indirect bandedges are extracted from the unfolded band structures. Based on a comparison within the same primitive unit cell, an efficient two band effective mass model for indirect conduction and valence valleys is created and parameterized by fitting the unfolded band structures. With the two band effective mass model, transport properties - specifically, we calculate the ballistic transmission in arbitrarily twisted bilayer $\textrm{MoS}_2$.