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For graphene films, the change of crystal structure induced by ion bombardment as well as the doping and strain generated in thermal annealing process is addressed in this work. Experimental results show that both the structure and number of defects for graphene depends strongly on the ion dose. Furthermore, it is found that the structure defects caused by ion bombardment in graphene can be healed and the graphene samples are all doped in subsequent thermal annealing. The frequency shift of G and 2D peaks in Raman spectra reveals that compressive strain in graphene results from the thermal annealing treatment and the occurrence of strain is influenced by the thermal annealing and defects in graphene. For graphene, since defects and thermal annealing are unavoidable for the fabrication of graphene-based devices, the systematical investigation on these two aspects in this work is, therefore, of great importance and significance. [ABSTRACT FROM AUTHOR]

The effect of ion-induced defects on graphene was studied to investigate the contact resistance of 40 nm palladium (Pd) contacting on graphene. The defect development was considered and analyzed by irradiating boron (B), carbon (C), nitrogen (N2), and argon (Ar) ions on as-transferred graphene before metallization. The bombardment energy was set at 1.5 keV and ion dose at 1 × 1014 ions/cm2. The defect yields under different ion irradiation conditions were examined by Raman spectroscopy. Although, dissolution process occurs spontaneously upon metal deposition, chemical reaction between metal and graphene is more pronounced at higher temperatures. The rapid thermal annealing (RTA) treatment was performed to improve the Pd/graphene contact after annealing at 450 °C, 500 °C, 550 °C, and 600 °C. The lowest contact resistance of 95.2 Ω-µm was achieved at 550 °C RTA with Ar ion irradiation. We have proved that ion irradiation significantly enhance the Pd/graphene contact instead of pd/pristine graphene contact. Therefore, in view of the contention of results ion induced defects before metallization plus the RTA served an excellent purpose to reduce the contact resistance. [ABSTRACT FROM AUTHOR]