Polarity Tunable Trionic Electroluminescence in Monolayer WSe<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 31517494.
- Also identified by DOI 10.1021/acs.nanolett.9b03215.
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Abstract
Monolayer WSe<sub>2</sub> exhibits luminescence arising from various types of exciton complexes due to strong many-body effects. Here, we demonstrate selective electrical excitation of positive and negative trions in van der Waals metal-insulator-semiconductor (MIS) heterostructure consisting of few-layer graphene (FLG), hexagonal boron nitride (hBN), and monolayer WSe<sub>2</sub>. Intentional unbalanced injection of electrons and holes is achieved via field-emission tunneling and electrostatic accumulation. The device exhibits planar electroluminescence from either positive trion X<sup>+</sup> or negative trion X<sup>-</sup> depending on the bias conditions. We show that hBN serves as a tunneling barrier material allowing selective injection of electron or holes into WSe<sub>2</sub> from FLG layer. Our observation offers prospects for hot carrier injection, trion manipulation, and on-chip excitonic devices based on two-dimensional semiconductors.