Enhanced terahertz detection of multigate graphene nanostructures

Area of Science:

• Optoelectronics
• Condensed Matter Physics
• Nanotechnology

Background:

• Terahertz (THz) waves offer potential for diverse applications, but require high-performance detectors.
• Graphene plasmonic THz detectors show promise but need performance improvements.

Purpose of the Study:

• To fabricate and characterize an asymmetric-dual-grating-gate graphene-terahertz-field-effect-transistor (G-THz-FET) for enhanced THz detection.
• To investigate the effect of biased gates on junction formation and THz signal rectification.

Main Methods:

• Fabrication of a G-THz-FET using a h-BN/Graphene/h-BN/Graphite heterostructure with double asymmetric-grating top-gates and a graphite back-gate.
• Characterization under 0.3 THz radiation at temperatures from 4.5 K to room temperature.
• Biasing metallic top-gates and graphite back-gate to form n, p, or np junctions.

Main Results:

• Biasing gates created abrupt n, p, or np junctions, enhancing the THz rectified signal by approximately tenfold.
• Plasmonic rectification in np junctions was attributed to the electron-hole ratchet mechanism.
• Rectification in n junctions was explained by the differential plasmonic drag effect.

Conclusions:

• The asymmetric-dual-grating-gate G-THz-FET design offers a new method for enhancing detector responsivity.
• This work advances graphene-based THz nano-photodetector performance towards new record levels.