Single Defect Light-Emitting Diode in a van der Waals Heterostructure

Area of Science:

• Materials Science
• Quantum Technology
• Condensed Matter Physics

Background:

• Single defects in tungsten diselenide (WSe2) monolayers are promising single photon emitters.
• Previous studies relied on optical excitation, limiting integration into quantum devices.
• Developing electrically driven sources is crucial for scalable quantum applications.

Purpose of the Study:

• To demonstrate electrically driven single photon emission from single defects in WSe2.
• To investigate the properties of electroluminescence from these defects.
• To explore the potential of van der Waals heterostructures for on-chip quantum light sources.

Main Methods:

• Fabrication of vertical and lateral van der Waals heterostructure devices using WSe2 monolayers.
• Integration of few-layer graphene as source/drain electrodes and hexagonal boron nitride as dielectric spacers.
• Utilizing a split back gate design for electrostatic p-i-n junction formation in lateral devices.
• Characterization of electroluminescence (EL) spectra at low temperatures (∼5 K).

Main Results:

• Successful observation of electrically driven single defect light emission in WSe2 heterostructures.
• EL spectra exhibit narrow lines consistent with optically excited defect bound excitons.
• Emission is spatially localized, with single defect spectra showing characteristic exchange splitting and linear polarization.
• Results align with previously reported optical measurements of single photon emitters.

Conclusions:

• Electrically driven single photon emission from single defects in WSe2 is feasible using van der Waals heterostructures.
• These findings enable the development of on-chip, electrically controlled single photon sources.
• The study advances the potential for 2D semiconductor-based quantum technologies.