Effect of oxygen plasma etching on graphene studied using Raman spectroscopy and electronic transport measurements

In this paper, we report a study of graphene and graphene field effect devices after their exposure to a series of short pulses of oxygen plasma. Our data from Raman spectroscopy, back-gated field-effect and magnetotransport measurements are presented. The intensity ratio between Raman ‘D’ and ‘G’ peaks, ID/IG (commonly used to characterize disorder in graphene), is observed to initially increase almost linearly with the number (Ne) of plasma-etching pulses, but later decreases at higher Ne values. We also discuss the implications of our data for extracting graphene crystalline domain sizes from ID/IG. At the highest Ne value measured, the ‘2D’ peak is found to be nearly suppressed while the ‘D’ peak is still prominent. Electronic transport measurements in plasma-etched graphene show an up-shifting of the Dirac point, indicating hole doping. We also characterize mobility, quantum Hall states, weak localization and various scattering lengths in a moderately etched sample. Our findings are valuable for understanding the effects of plasma etching on graphene and the physics of disordered graphene through artificially generated defects. 4 Author to whom any correspondence should be addressed. New Journal of Physics 13 (2011) 025008 1367-2630/11/025008+12$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft