Accessing the transport properties of graphene and its multi-layers at high carrier density

J. T. Ye, M. F. Craciun, M. Koshino, S. Russo, S. Inoue, H. T. Yuan, H. Shimotani, A. F. Morpurgo, Y. Iwasa

Published 2010-10-22Version 1

We present a comparative study of high carrier density transport in mono-, bi-, and trilayer graphene using electric-double-layer transistors to continuously tune the carrier density up to values exceeding 10^{14} cm^{-2}. Whereas in monolayer the conductivity saturates, in bi- and trilayer flling of the higher energy bands is observed to cause a non-monotonic behavior of the conductivity, and a large increase in the quantum capacitance. These systematic trends not only show how the intrinsic high-density transport properties of graphene can be accessed by field-effect, but also demonstrate the robustness of ion-gated graphene, which is crucial for possible future applications.