Quantum plasmonic two-dimensional WS₂-MoS₂ heterojunction.

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Two-dimensional (2D) heterostructures offer unique physical effects for advanced devices.
• Characterizing 2D lateral heterojunctions requires nano-optical techniques beyond the diffraction limit.
• Limited spatial resolution hinders complete optical property analysis of 2D heterojunctions.

Purpose of the Study:

• To investigate the optical properties of lateral monolayer WS₂-MoS₂ heterostructures.
• To explore subdiffraction limited tip-enhanced photoluminescence (TEPL) spectroscopy for characterization.
• To understand the quantum plasmonic effects in 2D heterojunctions.

Main Methods:

• Utilized subdiffraction limited tip-enhanced photoluminescence (TEPL) spectroscopy.
• Employed a plasmonic Au-Au tip-substrate picocavity with sub-nanometer tip-sample control.
• Developed a theoretical model for quantum plasmonic 2D heterojunctions.

Main Results:

• Achieved over 3 orders of magnitude photoluminescence (PL) enhancement at the heterojunction.
• Observed hot electron tunneling from the Au tip to MoS₂, quenching its PL.
• Simultaneously observed increased WS₂ PL due to resonant energy transfer, validated by simulations.

Conclusions:

• Demonstrated controllable photoresponse in 2D heterojunctions via quantum plasmonic effects.
• The study reveals a transition between classical and quantum regimes based on parameters.
• Findings pave the way for novel nanodevices utilizing tailored optical responses.