▎ 摘　　要

Identifying the role of defects that limits graphene's quality is important for various graphene devices on SiO2. In this paper, monolayer graphene samples with defect densities varying from similar to 0.04 mu m(-2) to similar to 10 mu m(-2) on SiO2 are characterized by both microscopic imaging and electrical transport measurements. We found that the height of graphene on SiO2 is directly related to its defect densities with a reverse correlation, which in turn degrade graphene's quality through a complicated mechanism rather than defects scattering only. We suggest that, at relative high defect density regime, graphene-SiO2 coupling is greatly enhanced causing an increasing charged impurity scattering significantly. (C) 2014 AIP Publishing LLC.