Giant Light Emission Enhancement in Strain-Engineered InSe/MS₂ (M = Mo or W) van der Waals Heterostructures.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) heterostructures (HSs) offer tunable properties but achieving optimal band alignment and charge transfer for high-performance devices remains challenging.
• Current methods for designing ideal HSs lack fine-tuning capabilities.
• The weak photoluminescence of Indium Selenide (InSe) limits its optoelectronic applications.

Purpose of the Study:

• To investigate the use of layer-selective strain engineering as a novel method to tailor the band alignment and optical properties of 2D HSs.
• To enhance the photoluminescence of InSe within InSe/MS2 (M = Mo or W) heterostructures.
• To demonstrate a new pathway for optimizing 2D heterostructures for optoelectronics.

Main Methods:

• Fabrication of InSe/MS2 (M = Mo or W) heterostructures.
• Application of layer-selective strain engineering to MS2 monolayers within the heterostructures.
• Photoluminescence spectroscopy to measure emission properties.
• First-principles calculations and resonant excitation measurements to understand charge transfer mechanisms.

Main Results:

• Selective strain application to MS2 monolayers resulted in a significant photoluminescence enhancement of InSe, exceeding 2 orders of magnitude.
• Evidence of strain-activated charge transfer from MS2 to InSe was observed.
• The band alignment and optical properties of the 2D HSs were successfully tailored via strain engineering.

Conclusions:

• Layer-selective strain engineering is a powerful tool for optimizing the optoelectronic properties of 2D heterostructures.
• This approach significantly enhances the emission of weakly emitting materials like InSe, expanding their potential applications.
• The findings pave the way for designing next-generation optoelectronic devices with improved performance.