# Sub-bandgap voltage electroluminescence and magneto-oscillations in a WSe2 light-emitting van der Waals heterostructure

## TL;DR

This study investigates electroluminescence and magneto-oscillations in a WSe2 van der Waals heterostructure, revealing low-threshold emission, Coulomb interaction effects, and magnetic field-induced oscillations linked to Landau quantization.

## Contribution

It demonstrates low-threshold electroluminescence driven by excitonic tunneling and uncovers magneto-oscillations related to Landau levels in a WSe2 heterostructure.

## Key findings

- Electroluminescence threshold below monolayer WSe2 band gap.
- Magneto-oscillations in electroluminescence with 1/B periodicity.
- Fermi level pinning and acceptor binding energy estimation.

## Abstract

We report on experimental investigations of an electrically driven WSe2 based light-emitting van der Waals heterostructure. We observe a threshold voltage for electroluminescence significantly lower than the corresponding single particle band gap of monolayer WSe2. This observation can be interpreted by considering the Coulomb interaction and a tunneling process involving excitons, well beyond the picture of independent charge carriers. An applied magnetic field reveals pronounced magneto-oscillations in the electroluminescence of the free exciton emission intensity with a 1/B-periodicity. This effect is ascribed to a modulation of the tunneling probability resulting from the Landau quantization in the graphene electrodes. A sharp feature in the differential conductance indicates that the Fermi level is pinned and allows for an estimation of the acceptor binding energy.