Ab initio study on the atomic and electronic structures of twisted InSe bilayer

TL;DR

This study uses large-scale density functional theory to analyze the electronic structures of twisted InSe bilayers, revealing how twisting affects band properties and exciton energies, with implications for layered material engineering.

Contribution

It provides a detailed ab initio analysis of twisted InSe bilayers, showing how twisting and interlayer distance influence electronic and excitonic properties, and extends the approach to heterostructures.

Findings

Twisted InSe bilayer's electronic structure can be described by features of aligned bilayers.

Hole effective mass is primarily affected by interlayer distance.

Exciton binding energies are calculated based on a recent theoretical model.

Abstract

The electronic properties of the twisted InSe bilayer are studied by large-scale density functional theory. Spectral Function Unfolding reveals that the electronic structure of the twisted system can be described in terms of a combination of features of the bandstructures of the aligned InSe bilayer with different stacking configurations, enabling predictions of the band gap and the effective mass for holes. The effective mass for holes in the twisted InSe bilayer is shown to be influenced primarily by the interlayer distance. The intralayer and interlayer exciton binding energies are thus calculated based on a model recently developed by Ruiz-Tijerina et al. We apply similar analysis to the trilayer heterostructure InSe/hBN/InSe: its electronic structure is shown to be well-described by the superposition of band structures of two InSe monolayers with a small coupling through the hBN layer.