High-performance terahertz modulators induced by substrate field in Te-based all-2D heterojunctions.

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• High-performance terahertz modulators are crucial for advanced communication.
• Existing modulators face a trade-off between modulation depth and speed.
• Two-dimensional (2D) materials offer potential for improved modulator performance.

Purpose of the Study:

• To introduce 2D tellurium (Te) nanofilms as a novel class of optically controlled terahertz modulators.
• To demonstrate that integrated Te nanofilm heterojunctions can overcome existing performance limitations.
• To investigate the influence of stacking order and underlying physical mechanisms on device performance.

Main Methods:

• Fabrication and characterization of 2D Te nanofilm heterojunctions.
• Optical control and photoresponse measurements of terahertz modulation.
• First-principles calculations to elucidate substrate-induced electric fields and carrier dynamics.

Main Results:

• Integrated Te nanofilm heterojunctions achieve optimal modulation depth and speed among all-2D broadband modulators.
• Photoresponse measurements reveal the significant impact of stacking order on device performance.
• First-principles calculations clarify substrate effects and uncover unusual photoexcited carrier dynamics, including charge transfer and interlayer exciton recombination.

Conclusions:

• 2D Te nanofilms represent a promising new material for high-performance terahertz modulators.
• Heterojunction engineering and stacking order are key to optimizing terahertz modulator performance.
• This work advances the fundamental understanding and application of Te nanomaterials in terahertz optoelectronics.