Substitutional Doping of Graphene via Hyperthermal Ion Implantation (HyTII)

The ability to manipulate materials with atomic precision is central to nanoscience. Hyperthermal ion implantation (HyTII) is a kinetic approach to doping with sub-nanometer control and is ideally suited for modifying 2D nanomaterials like graphene, yet few experimental studies have capitalized on this potential.$^{1}$ In this presentation, we experimentally investigate the effects of nitrogen ion implantation (N-HyTII) with ion energies ranging from 25 -- 100 eV and doses up to 10$^{15}$ N$^{+}$/cm$^{2}$. Following N-HyTII processing and transferring the graphene to a SiO$_{2}$/Si substrate, we collect Raman spatial maps over the entire sample surface, and perform XPS and STM analysis on a subset of the variable-energy samples along with HOPG as a control. The STM and XPS analysis confirm the substitutional incorporation of N into the graphene lattice at 45 eV, while the Raman D-peak to D`-peak ratios reveal distinct differences over the full energy range that are consistent with the different hyperthermal ion-substrate interactions pertaining to surface adsorption, substitutional doping, defect formation. We conclude this study by demonstrating the use of HyTII in graphene device processing, and highlight the effects of N-doping on the magnetotransport properties of graphene.$^{2}$ References: [1] C.D. Cress, et al. \textit{ACS Nano} \textbf{10}, 3714 (2016). [2] A.L. Friedman, et al. \textit{Phys. Rev. B}, \textbf{93} 161409(R) (2016).