Probing the Role of Interlayer Coupling and Coulomb Interactions on Electronic Structure in Few-Layer MoSe2 Nanostructures

TL;DR

This study combines experimental and theoretical approaches to investigate how interlayer coupling and Coulomb interactions influence the electronic structure of few-layer MoSe2, revealing significant bandgap reduction and wave function hybridization with increasing layers.

Contribution

It provides a detailed analysis of the layer-dependent electronic properties of MoSe2, highlighting the roles of interlayer coupling and electron-electron interactions in 2D heterostructures.

Findings

Bandgap decreases by nearly 1 eV from monolayer to trilayer

Electronic wave functions hybridize with increasing layers

Interlayer interactions significantly affect electronic properties

Abstract

Despite the weak nature of interlayer forces in transition metal dichalcogenide (TMD) materials, their properties are highly dependent on the number of layers in the few-layer two-dimensional (2D) limit. Here, we present a combined scanning tunneling microscopy/spectroscopy and GW theoretical study of the electronic structure of high quality single- and few-layer MoSe2 grown on bilayer graphene. We find that the electronic (quasiparticle) bandgap, a fundamental parameter for transport and optical phenomena, decreases by nearly one electronvolt when going from one layer to three due to interlayer coupling and screening effects. Our results paint a clear picture of the evolution of the electronic wave function hybridization in the valleys of both the valence and conduction bands as the number of layers is changed. This demonstrates the importance of layer number and electron-electron interactions on van der Waals heterostructures, and helps to clarify how their electronic properties might be tuned in future 2D nanodevices.