Broadband Perfect Absorber with Monolayer MoS₂ and Hexagonal Titanium Nitride Nano-disk Array.

Area of Science:

• Plasmonics and Nanophotonics
• Materials Science
• Optical Engineering

Background:

• Metamaterial absorbers (MAs) are crucial for various optical applications.
• Titanium nitride (TiN) offers excellent plasmonic properties in the visible spectrum.
• Molybdenum disulfide (MoS2) exhibits strong light absorption, particularly at shorter wavelengths.

Purpose of the Study:

• To design and investigate a broadband metamaterial absorber with high absorption efficiency.
• To explore the synergistic effects of TiN nano-disks and MoS2 for enhanced light absorption.
• To evaluate the absorber's performance across the visible spectrum and its polarization independence.

Main Methods:

• Finite-difference time-domain (FDTD) simulations were employed to model the metamaterial structure.
• The absorber design incorporates a TiN nano-disk array, a SiO2 dielectric layer, and an Al ground plane.
• Optimization of structural dimensions was performed to maximize absorption.
• Integration of a monolayer MoS2 layer was studied to enhance absorption at shorter wavelengths.

Main Results:

• An average absorption of 96.1% was achieved from 400 to 850 nm with the TiN nano-disk array structure.
• Incorporating monolayer MoS2 significantly boosted the average absorption to 98.1% over the 400-850 nm range.
• The absorber demonstrated peak absorption near 100% and maintained over 99% absorption from 475 to 772 nm.
• The designed absorber was found to be polarization insensitive.

Conclusions:

• The developed TiN nano-disk/monolayer MoS2/SiO2/Al structure functions as a highly efficient broadband metamaterial absorber.
• The integration of MoS2 effectively enhances absorption in the visible regime.
• This compact and polarization-insensitive absorber holds significant potential for applications in photovoltaics and light trapping.