Photocurrent in graphene harnessed by tunable intrinsic plasmons

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Graphene exhibits tunable optical properties in infrared and terahertz frequencies when patterned into metamaterials.
• Sub-wavelength patterning of graphene enhances its optical response for device applications.

Purpose of the Study:

• To demonstrate polarization-sensitive and gate-tunable photodetection using graphene nanoribbon arrays.
• To investigate the role of hybrid plasmon-phonon modes in graphene-based photodetectors.

Main Methods:

• Fabrication of graphene nanoribbon arrays with sub-wavelength features.
• Utilizing coupled excitations of electron density oscillations and substrate (SiO2) surface polar phonons (hybrid plasmon-phonon modes).
• Characterizing photocurrent response under different polarizations (s- and p-polarization) and gate tunability.

Main Results:

• Achieved an order of magnitude larger photocurrent for s-polarized excitation due to hybrid plasmon-phonon mode resonance compared to p-polarized excitation.
• Observed photo-induced temperature increases up to four times higher in plasmonic detectors versus 2D graphene detectors.
• Demonstrated polarization sensitivity in photocurrent sign for the narrowest nanoribbon arrays.

Conclusions:

• Graphene nanoribbon arrays with hybrid plasmon-phonon modes offer a pathway to highly sensitive and selective photodetectors.
• The findings highlight the potential of plasmonic excitations in graphene for advanced optoelectronic devices.
• This work enables the development of frequency-selective photodetectors leveraging graphene's unique plasmonic properties.