title: Photocurrent in graphene harnessed by tunable intrinsic plasmons.
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 photo-induced temperature increases up to four times as large as comparable two-dimensional graphene detectors. Moreover, the photocurrent sign becomes polarization sensitive in the narrowest nanoribbon arrays owing 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.
authors.affiliation: IBM Research Division, IBM TJ Watson Research Center, Yorktown Heights, New York, New York 10598, USA. mfreitag@us.ibm.com
authors.forename: Marcus
authors.initials: M
authors.lastname: Freitag
authors.forename: Tony
authors.initials: T
authors.lastname: Low
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Zhu
authors.forename: Hugen
authors.initials: H
authors.lastname: Yan
authors.forename: Fengnian
authors.initials: F
authors.lastname: Xia
authors.forename: Phaedon
authors.initials: P
authors.lastname: Avouris