Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p-n junctions
Jason S Ross1, Philip Klement2, Aaron M Jones3
1Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
Nature Nanotechnology
|March 11, 2014
Summary
Researchers achieved bright electroluminescence from monolayer tungsten diselenide (WSe2) using electrostatic gating. This breakthrough offers significantly improved efficiency and spectral properties for advanced optoelectronic devices.
Area of Science:
- Optoelectronics
- Materials Science
- Condensed Matter Physics
Background:
- Transition-metal dichalcogenides (TMDs) are promising for optoelectronics.
- Previous electroluminescence in monolayer MoS2 suffered from low efficiency and broad linewidths due to material quality and contact issues.
Purpose of the Study:
- To develop highly efficient and spectrally narrow electroluminescence from monolayer TMDs.
- To explore electrostatic induction of p-n junctions in WSe2 for enhanced optoelectronic performance.
Main Methods:
- Fabrication of lateral p-n junctions in monolayer WSe2 using electrostatic gating with a boron nitride dielectric.
- Utilizing multiple metal gates for effective electron and hole injection.
- Characterization of electroluminescence properties, including current, linewidth, and exciton dynamics.
Main Results:
- Achieved bright electroluminescence from WSe2 lateral p-n junctions.
- Demonstrated 1000x lower injection current and 10x narrower linewidth compared to MoS2 devices.
- Tuned electroluminescence by varying injection bias to control exciton regimes (impurity-bound, charged, neutral).
Conclusions:
- Electrostatically induced WSe2 p-n junctions offer superior electroluminescence performance.
- This system is suitable for developing novel optoelectronic devices like spin- and valley-polarized LEDs, on-chip lasers, and 2D electro-optic modulators.
