title: Nitrogen-Doped Graphene and Twisted Bilayer Graphene via Hyperthermal Ion Implantation with Depth Control.
abstract: We investigate hyperthermal ion implantation (HyTII) as a means for substitutionally doping layered materials such as graphene. In particular, this systematic study characterizes the efficacy of substitutional N-doping of graphene using HyTII over an N(+) energy range of 25-100 eV. Scanning tunneling microscopy results establish the incorporation of N substituents into the graphene lattice during HyTII processing. We illustrate the differences in evolution of the characteristic Raman peaks following incremental doses of N(+). We use the ratios of the integrated D and D' peaks, I(D)/I(D') to assess the N(+) energy-dependent doping efficacy, which shows a strong correlation with previously reported molecular dynamics (MD) simulation results and a peak doping efficiency regime ranging between approximately 30 and 50 eV. We also demonstrate the inherent monolayer depth control of the HyTII process, thereby establishing a unique advantage over other less-specific methods for doping. We achieve this by implementing twisted bilayer graphene (TBG), with one layer of isotopically enriched (13)C and one layer of natural (12)C graphene, and modify only the top layer of the TBG sample. By assessing the effects of N-HyTII processing, we uncover dose-dependent shifts in the transfer characteristics consistent with electron doping and we find dose-dependent electronic localization that manifests in low-temperature magnetotransport measurements.
authors.affiliation: Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States.
authors.forename: Cory D
authors.initials: CD
authors.lastname: Cress
authors.affiliation: National Research Council, U.S. Naval Research Laboratory , Washington, DC 20375, United States.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Schmucker
authors.affiliation: Material Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Friedman
authors.affiliation: National Research Council, U.S. Naval Research Laboratory , Washington, DC 20375, United States.|Department of Physics and Astronomy, Howard University , Washington, DC 20059, United States.
authors.forename: Pratibha
authors.initials: P
authors.lastname: Dev
authors.affiliation: Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States.
authors.forename: James C
authors.initials: JC
authors.lastname: Culbertson
authors.affiliation: Department of Electrical and Computer Engineering, and the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Lyding
authors.affiliation: Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States.
authors.forename: Jeremy T
authors.initials: JT
authors.lastname: Robinson
keywords: N-graphene; Raman; graphene; hyperthermal ion implantation (HyTII); nitrogen doping; twisted bilayer graphene (TBG)