title: Photoresponse of an electrically tunable ambipolar graphene infrared thermocouple.
abstract: We explore the photoresponse of an ambipolar graphene infrared thermocouple at photon energies close to or below monolayer graphene's optical phonon energy and electrostatically accessible Fermi energy levels. The ambipolar graphene infrared thermocouple consists of monolayer graphene supported by an infrared absorbing material, controlled by two independent electrostatic gates embedded below the absorber. Using a scanning infrared laser microscope, we characterize these devices as a function of carrier type and carrier density difference controlled at the junction between the two electrostatic gates. On the basis of these measurements, conducted at both mid- and near-infrared wavelengths, the primary detection mechanism can be modeled as a thermoelectric response. By studying the effect of different infrared absorbers, we determine that the optical absorption and thermal conduction of the substrate play the dominant role in the measured photoresponse of our devices. These experiments indicate a path toward hybrid graphene thermal detectors for sensing applications such as thermography and chemical spectroscopy.
authors.affiliation: Department of Physics, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Patrick K
authors.initials: PK
authors.lastname: Herring
authors.forename: Allen L
authors.initials: AL
authors.lastname: Hsu
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Gabor
authors.forename: Yong Cheol
authors.initials: YC
authors.lastname: Shin
authors.forename: Jing
authors.initials: J
authors.lastname: Kong
authors.forename: Tomás
authors.initials: T
authors.lastname: Palacios
authors.forename: Pablo
authors.initials: P
authors.lastname: Jarillo-Herrero