title: Photocurrent imaging and efficient photon detection in a graphene transistor.
abstract: We measure the channel potential of a graphene transistor using a scanning photocurrent imaging technique. We show that at a certain gate bias, the impact of the metal on the channel potential profile extends into the channel for more than one-third of the total channel length from both source and drain sides; hence, most of the channel is affected by the metal. The potential barrier between the metal-controlled graphene and bulk graphene channel is also measured at various gate biases. As the gate bias exceeds the Dirac point voltage, VDirac, the original p-type graphene channel turns into a p-n-p channel. When light is focused on the p-n junctions, an impressive external responsivity of 0.001 A/W is achieved, given that only a single layer of atoms are involved in photon detection.
authors.affiliation: IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA. fxia@ibm.com
authors.forename: Fengnian
authors.initials: F
authors.lastname: Xia
authors.forename: Thomas
authors.initials: T
authors.lastname: Mueller
authors.forename: Roksana
authors.initials: R
authors.lastname: Golizadeh-Mojarad
authors.forename: Marcus
authors.initials: M
authors.lastname: Freitag
authors.forename: Yu-ming
authors.initials: YM
authors.lastname: Lin
authors.forename: James
authors.initials: J
authors.lastname: Tsang
authors.forename: Vasili
authors.initials: V
authors.lastname: Perebeinos
authors.forename: Phaedon
authors.initials: P
authors.lastname: Avouris