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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, I-D/I-G (commonly used to characterize disorder in graphene), is observed to initially increase almost linearly with the number (N-e) of plasma-etching pulses, but later decreases at higher N-e values. We also discuss the implications of our data for extracting graphene crystalline domain sizes from I-D/I-G. At the highest N-e 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.
Childres et al. (Thu,) studied this question.