Suspended MoS₂ Photodetector Using Patterned Sapphire Substrate

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Two-dimensional (2D) layered materials, like molybdenum disulfide (MoS2), offer unique optoelectronic properties.
• Patterned sapphire substrates (PSS) are explored to enhance the performance of 2D material-based devices.
• MoS2 exhibits a promising photoresponse due to its direct-indirect bandgap transition at the monolayer.

Purpose of the Study:

• To investigate the effect of PSS on the photoelectric performance of MoS2 films.
• To analyze the underlying mechanisms, including electric field distribution and photon exciton concentration.
• To demonstrate enhanced photodetector capabilities for broad-spectrum detection.

Main Methods:

• Large-scale, continuous multilayer MoS2 films were prepared on SiO2/Si substrates.
• MoS2 films were transferred to both flat sapphire and PSS.
• Finite-difference time-domain (FDTD) simulations were used to analyze optical properties.

Main Results:

• FDTD simulations revealed enhanced local electric field distribution and concentrated photon excitons at the MoS2/PSS interface.
• Photodetector performance significantly improved under 365, 460, and 660 nm lasers when using PSS.
• Under 365 nm laser: photocurrent increased 3x, noise equivalent power (NEP) decreased to 1.77 × 10^-14 W/Hz^1/2, specific detectivity (D*) increased to 1.2 × 10^10 Jones.
• Under 460 nm laser: responsivity increased 7x.
• Response times were shortened across all tested wavelengths.

Conclusions:

• PSS effectively enhances the photoelectric performance of MoS2-based photodetectors.
• The enhanced performance is attributed to improved light management at the MoS2/PSS interface.
• This approach enables simultaneous detection of broad-spectrum light, advancing optoelectronic applications.