We investigate the effects of defect scatterings on the electric transport properties of chemical vapor deposited (CVD) graphene by measuring the carrier density dependence of the magneto-conductivity. To clarify the dominant scattering mechanism, we perform extensive measurements on large-area samples with different mobility to exclude the edge effect. We analyze our data with the major scattering mechanisms such as short-range static scatters, short-range screened Coulomb disorders, and weak-localization (WL). We establish that the charged impurities are the predominant scatters because there is a strong correlation between the mobility and the charge impurity density. Near the charge neutral point (CNP), the electron-hole puddles that are induced by the charged impurities enhance the inter-valley scattering, which is favorable for WL observations. Away from the CNP, the charged-impurity-induced scattering is weak because of the effective screening by the charge carriers. As a result, the local static structural defects govern the charge transport. Our findings provide compelling evidence for understanding the scattering mechanisms in graphene and pave the way for the improvement of fabrication techniques to achieve high-quality CVD graphene.
Bibliographical noteFunding Information:
We acknowledge Chung-Yu Mo, C. S. Ting, and Xin-Zhong Yan for helpful discussions and Ang-Yu Lu and J. Y. Juang for assistance with the experiments. This work was supported by the Department of Natural Science at the National Science Council under Grant No. NSC 101-2628-M-007-002-MY3, Taiwan.
ASJC Scopus subject areas
- General Physics and Astronomy