Plasmon-enhanced ultraviolet photoluminescence from hybrid structures of graphene/ZnO films.
We report substantially enhanced photoluminescence (PL) from hybrid structures of graphene/ZnO films at a band gap energy of ZnO (∼3.3  eV/376  nm). Despite the well-known constant optical conductivity of graphene in the visible-frequency regime, its abnormally strong absorption in the violet-frequency region has recently been reported. In this Letter, we demonstrate that the resonant excitation of graphene plasmon is responsible for such absorption and eventually contributes to enhanced photoemission from structures of graphene/ZnO films when the corrugation of the ZnO surface modulates photons emitted from ZnO to fulfill the dispersion relation of graphene plasmon. These arguments are strongly supported by PL enhancements depending on the spacer thickness, measurement temperature, and annealing temperature, and the micro-PL mapping images obtained from separate graphene layers on ZnO films.
Hwang
Sung Won
SW
Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
Shin
Dong Hee
DH
Kim
Chang Oh
CO
Hong
Seung Hui
SH
Kim
Min Choul
MC
Kim
Jungkil
J
Lim
Keun Yong
KY
Kim
Sung
S
Choi
Suk-Ho
SH
Ahn
Kwang Jun
KJ
Kim
Gunn
G
Sim
Sung Hyun
SH
Hong
Byung Hee
BH