Photocurrent in graphene harnessed by tunable intrinsic plasmons

TL;DR

This paper demonstrates polarization-sensitive, tunable graphene nanoribbon photodetectors leveraging hybrid plasmon-phonon modes, achieving enhanced photocurrent and temperature response for infrared and terahertz detection.

Contribution

It introduces a novel graphene-based photodetector design utilizing hybrid plasmon-phonon modes for tunable, polarization-sensitive detection with significantly improved performance.

Findings

Photocurrent is significantly larger for s-polarization due to hybrid plasmon-phonon excitation.

Photodetectors show up to four times higher temperature increase than standard graphene detectors.

Photocurrent polarity becomes polarization-sensitive in narrow nanoribbon arrays.

Abstract

Graphene's optical properties in the infrared and terahertz can be tailored and enhanced by patterning graphene into periodic metamaterials with sub-wavelength feature sizes. Here we demonstrate polarization sensitive and gate tunable photodetection in graphene nanoribbon arrays. The long-lived hybrid plasmon-phonon modes utilized are coupled excitations of electron density oscillations and substrate (SiO2) surface polar phonons. Their excitation by s-polarization leads to an in-resonance photocurrent an order of magnitude larger than the photocurrent observed for p-polarization, which excites electron-hole pairs. The plasmonic detectors exhibit photoinduced temperature increases up to four times as large as comparable 2D graphene detectors. Moreover, the photocurrent sign becomes polarization sensitive in the narrowest nanoribbon arrays due to differences in decay channels for photoexcited hybrid plasmon-phonons and electrons. Our work provides a path to light sensitive and frequency selective photodetectors based on graphene's plasmonic excitations.