Fast and Sensitive Terahertz Detection Using an Antenna-Integrated Graphene pn Junction

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Terahertz (THz) detection is crucial for various applications.
• Existing THz detectors face limitations in sensitivity, speed, operating temperature, and spectral range.

Purpose of the Study:

• To introduce a novel graphene-based detector for terahertz radiation.
• To overcome the limitations of current THz detectors using the photothermoelectric (PTE) effect.

Main Methods:

• Utilized graphene as the photoactive material.
• Designed a dual-gated, dipolar antenna with a narrow gap (∼100 nm).
• Integrated a graphene channel above the antenna to create a pn junction for photoresponse.

Main Results:

• Demonstrated excellent sensitivity with a noise-equivalent power of 80 pW/Hz^(1/2) at room temperature.
• Achieved a response time below 30 ns (setup-limited) and high dynamic range.
• Showcased broadband operation from 1.8–4.2 THz, fulfilling unmet needs in current detectors.

Conclusions:

• The novel graphene PTE detector offers superior performance compared to state-of-the-art devices.
• A deep understanding of the PTE effect in THz detection was achieved through experimental, analytical, and numerical studies.
• This work provides a valuable foundation for further optimization of THz detectors.