Atomistic Simulations of the Efficiencies of Ge and Pt Ion Implantation into Graphene

Recent success in the direct implantation of 74Ge+ ion, the heaviest atomic impurity to date, into monolayer graphene presents a general question of the efficiency of low-energy ion implantation technique for heavy atoms. A comparative computational study, using classical molecular dynamics, of low-energy Ge and Pt ions implantation into single- and double-layer graphene is presented. It confirms that the highest probability for the perfect substitutional doping of single-layer graphene, i.e., direct implanting of ion into monovacancy, can be achieved 80 eV and it reaches the value of 64% for Ge ions directed at 45° angle to graphene plane and 21% for Pt ion beam perpendicular to graphene. Implantation efficiency is strongly dependent on the angle of ion beam. The sputtering yield of carbon atoms is found to be lower for double layer of graphene, which has better protective properties against low-energy ion irradiation damage than a single graphene layer. In double-layer graphene, incident ions traveling in the direction perpendicular to graphene can be trapped between the layers with the highest efficiency above or equal to 80% in the energy range of 40–90 eV for Ge ions and above 90% in the energy range of 40–70 eV for Pt ions. The energy range corresponding to the efficient trapping of ions in double-layer graphene is shifted toward higher energies upon tilting of the angle of incident ion beam.