Photocurrent imaging and efficient photon detection in a graphene transistor.
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.
Xia
Fengnian
F
IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA. fxia@ibm.com
Mueller
Thomas
T
Golizadeh-Mojarad
Roksana
R
Freitag
Marcus
M
Lin
Yu-ming
YM
Tsang
James
J
Perebeinos
Vasili
V
Avouris
Phaedon
P