J. Phys.: Condens. Matter 22, 045002 (2010)
N. García, Zang Yan, A. Ballestar, J. Barzola-Quiquia, F. Bern and P. Esquinazi
The electrical potential on the surface of ~300 nm thick SiO2 grown on single-crystalline Si substrates has been characterized at ambient conditions using electric field microscopy. Our results show an inhomogeneous potential distribution with fluctuations up to ~0.4 V within regions of 1 µm. The potential fluctuations observed at the surface of these usual dielectric holders of graphene sheets should induce strong variations in the graphene charge densities and provide a simple explanation for some of the anomalous behaviors of the transport properties of graphene.