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Defect Control and n‑Doping of Encapsulated Graphene by Helium-Ion-Beam Irradiation

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journal contribution
posted on 10.06.2015, 00:00 by Gaurav Nanda, Srijit Goswami, Kenji Watanabe, Takashi Taniguchi, Paul F. A. Alkemade
We study with Raman spectroscopy the influences of He+ bombardment and the environment on beam-induced defects in graphene encapsulated in hexagonal boron nitride (h-BN). We show for the first time experimentally the autonomous behavior of the D′ defect Raman peak: in contrast to the D defect peak, the D′ defect peak is sensitive to the local environment. In particular, it saturates with ion dose in the encapsulated graphene. Electrical measurements reveal n-type conduction in the BN-encapsulated graphene. We conclude that unbound atoms (“interfacials”) between the sp2-layers of graphene and h-BN promote self-healing of the beam-induced lattice damage and that nitrogen–carbon exchange leads to n-doping of graphene.