Inhomogeneity-Induced Carrier Transport Of Chemical Vapor Deposited Graphene On Hfo2 At Low Temperatures

We have investigated carrier transport properties of chemical vapor deposited graphene placed on HfO2/Si substrate. Due to the increased charged impurity scattering originating from the HfO2 substrate, the mobility of the graphene on HfO2 substrate was about 15 times lower than that on SiO2 substrate, and it was possible to explore the regime of k(F)l approximate to 1 even far from the Dirac point. The temperature dependence of resistivity showed a weakly insulating behavior which can be characterized by a combination of diffusive and thermally activated transport in the presence of electron-hole puddles. From the magnetic field dependence, a negative magnetoresistance that is characteristic of weak localization was observed and the intervalley scattering time was found to be larger than the phase coherence time. These behaviors are attributed to the formation of puddles in the presence of disorder in the system.