Probing charged impurities in suspended graphene using Raman spectroscopy.
Charged impurity (CI) scattering is one of the dominant factors that affects the carrier mobility in graphene. In this paper, we use Raman spectroscopy to probe the charged impurities in suspended graphene. We find that the 2D band intensity is very sensitive to the CI concentration in graphene, while the G band intensity is not affected. The intensity ratio between the 2D and G bands, I(2D)/I(G), of suspended graphene is much stronger compared to that of nonsuspended graphene, due to the extremely low CI concentration in the former. This finding is consistent with the ultrahigh carrier mobility in suspended graphene observed in recent transport measurements. Our results also suggest that at low CI concentrations that are critical for device applications, the I(2D)/I(G) ratio is a better criterion in selecting high quality single layer graphene samples than is the G band blue shift.
Ni
Zhen Hua
ZH
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore.
Yu
Ting
T
Luo
Zhi Qiang
ZQ
Wang
Ying Ying
YY
Liu
Lei
L
Wong
Choun Pei
CP
Miao
Jianmin
J
Huang
Wei
W
Shen
Ze Xiang
ZX