Open Access Nano Express

Layer-dependent nanoscale electrical properties of graphene studied by conductive scanning probe microscopy

Shihua Zhao, Yi Lv and Xinju Yang*

Author Affiliations

State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China

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Nanoscale Research Letters 2011, 6:498  doi:10.1186/1556-276X-6-498

Published: 18 August 2011

Abstract

The nanoscale electrical properties of single-layer graphene (SLG), bilayer graphene (BLG) and multilayer graphene (MLG) are studied by scanning capacitance microscopy (SCM) and electrostatic force microscopy (EFM). The quantum capacitance of graphene deduced from SCM results is found to increase with the layer number (n) at the sample bias of 0 V but decreases with n at -3 V. Furthermore, the quantum capacitance increases very rapidly with the gate voltage for SLG, but this increase is much slowed down when n becomes greater. On the other hand, the magnitude of the EFM phase shift with respect to the SiO2 substrate increases with n at the sample bias of +2 V but decreases with n at -2 V. The difference in both quantum capacitance and EFM phase shift is significant between SLG and BLG but becomes much weaker between MLGs with a different n. The layer-dependent quantum capacitance behaviors of graphene could be attributed to their layer-dependent electronic structure as well as the layer-varied dependence on gate voltage, while the layer-dependent EFM phase shift is caused by not only the layer-dependent surface potential but also the layer-dependent capacitance derivation.

Keywords:
graphene; scanning capacitance microscopy; electrostatic force microscopy; layer dependence; quantum capacitance