Electrically tunable layer-hybridized trions in doped WSe₂ bilayers

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Doped van der Waals heterostructures exhibit layer-hybridized trions, which are charged excitons with delocalized constituents.
• These trions offer potential for advanced optoelectronic devices due to their controllability.

Purpose of the Study:

• To investigate the electrical tunability of trion energy landscapes in WSe2 bilayers.
• To understand the impact of electric fields on the properties and behavior of layer-hybridized trions.

Main Methods:

• Combined a microscopic theory with photoluminescence (PL) experiments.
• Utilized naturally stacked WSe2 bilayers and applied out-of-plane electric fields.
• Analyzed the energetic ordering and PL signatures of trion states under varying electric fields and doping.

Main Results:

• An out-of-plane electric field modifies the energetic ordering of lowest-lying trion states (layer-hybridized electrons, layer-localized holes).
• At low fields, intralayer-like trions show distinct PL signatures with weak Stark shifts.
• Above a critical field, interlayer-like trions become dominant, exhibiting a pronounced Stark red-shift and enhanced intensity due to phonon-assisted recombination.

Conclusions:

• The study provides a deeper microscopic understanding of layer-hybridized trions in van der Waals heterostructures.
• Demonstrates electrical control over trion states, paving the way for novel optoelectronic applications.
• Highlights the potential of electrically tunable atomically-thin semiconductors for future devices.