Abstract
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.
Highlights
A search for new functionalities and applications of graphene has intensified since its discovery, 1,2 often through chemical modification or altering its structure by implantation of new atomic species using low energy ion beam irradiation. 3–5 Metal decorated graphene offers an attractive hybrid material for low dimensional magnetic ordering and spintronics, 6 with applications in electrocatalysis, fuel cells, energy production and storage, as well as electrochemical sensing. 7 Typical values for the binding energy of metal ad-atom to pristine graphene range between 0.2 eV and 1.5 eV with the migration barrier of 0.2 - 0.8 eV, 8 indicating its high mobility on graphene at room temperature
Previous studies show that a single metal atom can be trapped in graphene vacancies created by electron beam irradiation, notably assisted by the electron impacts in transmission electron micrsoscopy experiments. 9,10 Metal atom trapped in a single or double vacancy could exhibit interesting dynamic behaviour under electron beam as the values of the threshold energies for ejection of carbon atoms neighbouring metal impurity are lower than those in pristine graphene
Implantation of Ge an Pt atoms in single and double layer graphene using low energy ion irradiation was studied by molecular dynamics simulations
Summary
A search for new functionalities and applications of graphene has intensified since its discovery, 1,2 often through chemical modification or altering its structure by implantation of new atomic species using low energy ion beam irradiation. 3–5 Metal decorated graphene offers an attractive hybrid material for low dimensional magnetic ordering and spintronics, 6 with applications in electrocatalysis, fuel cells, energy production and storage, as well as electrochemical sensing. 7 Typical values for the binding energy of metal ad-atom to pristine graphene range between 0.2 eV and 1.5 eV with the migration barrier of 0.2 - 0.8 eV, 8 indicating its high mobility on graphene at room temperature. 7 Typical values for the binding energy of metal ad-atom to pristine graphene range between 0.2 eV and 1.5 eV with the migration barrier of 0.2 - 0.8 eV, 8 indicating its high mobility on graphene at room temperature. 9,10 Metal atom trapped in a single or double vacancy could exhibit interesting dynamic behaviour under electron beam as the values of the threshold energies for ejection of carbon atoms neighbouring metal impurity are lower than those in pristine graphene. This has been illustrated recently by the case of Fe atom trapped in graphene vacancies. It has been shown to be effective for direct substitution of single carbon atoms in graphene with light atomic impurities such as silicon, 13–15 phosphorus, 16 nitrogen and boron, 17,18 and for intercalation of atoms between graphene layers. 19
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