Structural defects dependence of the second-harmonic generation in monolayer MoS₂

Area of Science:

• Materials Science
• Optics and Photonics
• Condensed Matter Physics

Background:

• Second-harmonic generation (SHG) is vital for material characterization and laser wavelength extension.
• Defects in transition metal dichalcogenides (TMDs) like MoS2 are unavoidable but can be engineered.
• Understanding defect impact on MoS2 SHG is critical for applications.

Purpose of the Study:

• To systematically investigate how defect type and concentration influence MoS2 SHG properties.
• To demonstrate directional tuning of SHG in monolayer MoS2 via defect engineering.

Main Methods:

• Selective introduction of specific point defects (V_S, V_S2, Mo_S, V2_S2, V_Mo) in monolayer MoS2.
• Accurate control over defect density.
• Analysis of SHG properties across visible to near-infrared and communication bands.

Main Results:

• Demonstrated precise control over SHG properties of MoS2 by engineering point defects.
• Achieved directional tuning of SHG across a broad spectral range (visible to communication bands).
• Showcased the potential for tailoring SHG response through defect concentration.

Conclusions:

• Defect engineering offers a powerful route to tune SHG in MoS2.
• Findings provide a theoretical basis for developing broadband frequency converters.
• Enables the design of communication-band SHG devices through controlled defect introduction.