Excited Rydberg States in TMD Heterostructures

TL;DR

This study measures excitonic energy levels in MoSe2/WSe2 heterostructures using resonance Raman spectroscopy, validating a Coulomb interaction model that predicts exciton energies with high accuracy, aiding future TMD device design.

Contribution

The paper introduces a validated Coulomb potential model for TMD heterostructures based on resonance Raman measurements, improving understanding of excitonic properties.

Findings

Excitonic energy levels measured with ~5 meV accuracy.

Model predicts exciton energies within 2.5%.

Heterostructure formation affects single-particle band gaps.

Abstract

The functional form of Coulomb interactions in the transition metal dichalcogenides and other van der Waals solids is critical to many of their unique properties, e.g. strongly-correlated electron states, superconductivity and emergent ferromagnetism. This paper presents measurements of key excitonic energy levels in MoSe2/WSe2 heterostructures. These measurements are obtained from resonance Raman experiments on specific Raman peaks only observed at excited states of the excitons. This data is used to validate a model of the Coulomb potential in these structures which predicts the exciton energies to within ~5 meV / 2.5%. This model is used to determine the effect of heterostructure formation on the single-particle band gaps of the layers and will have a wide applicability in designing the next generation of more complex transition metal dichalcogenide structures.