Localization and interaction of interlayer excitons in MoSe₂/WSe₂ heterobilayers.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Transition metal dichalcogenide (TMD) heterobilayers are platforms for studying excitonic physics.
• Interlayer excitons (IXs) can exist as localized or delocalized states within these heterobilayers.
• The precise nature of IX localization and biexciton formation in TMDs remains unclear.

Purpose of the Study:

• To investigate the localization of interlayer excitons (IXs) in different potential traps.
• To explore the emergence of interlayer biexcitons under high excitation.
• To understand the impact of potential traps on IX and biexciton behavior in MoSe2/WSe2 heterobilayers.

Main Methods:

• Fabrication and optical characterization of MoSe2/WSe2 heterobilayers.
• Temperature-dependent photoluminescence spectroscopy.
• High excitation intensity measurements.

Main Results:

• Two distinct types of potential traps were identified in the MoSe2/WSe2 heterobilayer.
• These traps, attributed to defect states and moiré potential, significantly affect IX emission behavior with temperature.
• Superlinear emission under high excitation confirmed the emergence of interlayer biexcitons, with peak formation at a specific temperature.

Conclusions:

• The study elucidates the roles of defect states and moiré potential in IX localization.
• Different excitation and temperature regimes are crucial for controlling localized/delocalized IX and biexciton formation.
• Findings advance the understanding and application of exciton physics in TMD heterostructures.