Determination of dominant scatterer in Graphene on SiO$_2$ using atomic hydrogen

We have measured the impact of low energy atomic hydrogen (\textless\ 250meV) on the transport property of graphene sheets as a function of hydrogen coverage and initial, pre-hydrogenation field-effect mobility. In order to understand the correlation between the field effect mobility and the apparent affinity of atomic hydrogen to graphene, we have performed a detailed temperature programmed desorption study on hydrogen-dosed graphene sheets. Atomic hydrogen is found to be desorbing with three different desorption energies. The physisorbed atomic hydrogen on graphene with desorption energy of 60 $\pm$ 30meV (consistent with our theoretical calculations), is found to be correlated to the native scatterers in graphene. The associated charge transfer expected for such small desorption energy indicates that atomic-scale defect sites are not responsible for determining the mobility of graphene on SiO$_{2}$ and that charged impurities, presumably in substrates, define the transport property of graphene on SiO$_{2}$.