Hot carrier multiplication on graphene/TiO2 Schottky nanodiodes.
Carrier multiplication (i.e. generation of multiple electron-hole pairs from a single high-energy electron, CM) in graphene has been extensively studied both theoretically and experimentally, but direct application of hot carrier multiplication in graphene has not been reported. Here, taking advantage of efficient CM in graphene, we fabricated graphene/TiO2 Schottky nanodiodes and found CM-driven enhancement of quantum efficiency. The unusual photocurrent behavior was observed and directly compared with Fowler's law for photoemission on metals. The Fowler's law exponent for the graphene-based nanodiode is almost twice that of a thin gold film based diode; the graphene-based nanodiode also has a weak dependence on light intensity-both are significant evidence for CM in graphene. Furthermore, doping in graphene significantly modifies the quantum efficiency by changing the Schottky barrier. The CM phenomenon observed on the graphene/TiO2 nanodiodes can lead to intriguing applications of viable graphene-based light harvesting.
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.|Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Young Keun
YK
Lee
Creative Research Center for Graphene Electronics, Electronics and Telecommunications Research Institute (ETRI), Gajeongno, Yuseong-gu, Daejeon, 305-700, Republic of Korea.
Hongkyw
H
Choi
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.|Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Hyunsoo
H
Lee
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.|Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Changhwan
C
Lee
Creative Research Center for Graphene Electronics, Electronics and Telecommunications Research Institute (ETRI), Gajeongno, Yuseong-gu, Daejeon, 305-700, Republic of Korea.
Jin Sik
JS
Choi
Creative Research Center for Graphene Electronics, Electronics and Telecommunications Research Institute (ETRI), Gajeongno, Yuseong-gu, Daejeon, 305-700, Republic of Korea.
Choon-Gi
CG
Choi
SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
Euyheon
E
Hwang
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.|Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
Jeong Young
JY
Park