Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe<sub>2</sub> Light-Emitting van der Waals Heterostructure.
basic_science · Level V
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- Record sourced from PubMed, PMID 28211273.
- Also identified by DOI 10.1021/acs.nanolett.6b04374.
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Abstract
We report on experimental investigations of an electrically driven WSe<sub>2</sub> 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 WSe<sub>2</sub>. 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.