Metasurface-Enhanced Infrared Photodetection Using Layered van der Waals MoSe₂.

Area of Science:

• Materials Science
• Nanophotonics
• Optoelectronics

Background:

• Transition metal dichalcogenides (TMDs) show promise for photodetection but are limited by their intrinsic bandgaps, restricting broadband performance.
• TMDs struggle to absorb photons with energies below their bandgap, causing significant photoresponse attenuation in longer wavelengths.
• Traditional semiconductor doping processes often require high temperatures, posing integration challenges with 2D materials.

Purpose of the Study:

• To investigate metasurface-enhanced two-dimensional molybdenum diselenide (MoSe2) photodetectors.
• To demonstrate broadband responsivity extension into the mid-infrared spectrum using metasurface engineering.
• To provide experimental foundations for optimizing high-performance broadband photodetectors.

Main Methods:

• Fabrication of MoSe2 photodetectors integrated with subwavelength optical metasurface structures.
• Utilizing localized plasmon resonance effects through metasurface design to enhance light absorption in MoSe2 films.
• Systematic investigation and precise control of metasurface structural dimensions to tune optical absorption and spectral response.

Main Results:

• Achieved broadband spectral response from 808 nm to 10 μm in metasurface-enhanced MoSe2 photodetectors.
• Demonstrated significant enhancement in light absorption and photoresponse into the mid-infrared spectrum.
• Optimized device exhibited responsivity (R) of 7.1 mA/W and specific detectivity (D*) of 1.12 × 10^8 Jones at 4 μm illumination.

Conclusions:

• Metasurface integration overcomes the intrinsic bandgap limitations of TMDs for broadband photodetection.
• Precise control over metasurface dimensions enables tailoring of spectral response for specific applications.
• This work presents a viable strategy for developing advanced broadband optoelectronic devices through nanophotonic engineering.