We report the incorporation of substitutional Mn atoms in high-quality, epitaxial 1 graphene on Cu(111), using ultra-low energy ion implantation. We characterize in detail the atomic structure of substitutional Mn in a single carbon vacancy and quantify its concentration. In particular, we are able to determine the position of substitutional Mn atoms with respect to the Moiré superstructure (i.e. local graphene-Cu stacking symmetry) and to the carbon sublattice; in the out-of-plane direction, substitutional Mn atoms are found to be slightly displaced towards the Cu surface, i.e. effectively underneath the graphene layer. Regarding electronic properties, we show that graphene doped with substitutional Mn to a concentration of the order of 0.04%, with negligible structural disorder (other than the Mn substitution), retains the Dirac-like band structure of pristine graphene on Cu(111), making it an ideal system in which to study the interplay between local magnetic moments and Dirac electrons. Our work also establishes that ultra-low energy ion implantation is suited for substitutional magnetic doping of graphene; given the flexibility, reproducibility and scalability inherent to ion implantation, our work creates numerous opportunities for research on magnetic functionalization of graphene and other 2D materials.

Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent past. Intensive theoretical and experimental studies on such nanostructures at both the fundamental and application-oriented levels have been performed. The present paper discusses the suitability of graphene nanoribbons devices for nanoelectronics and focuses on three specific device types -graphene nanoribbon MOSFETs, side-gate transistors, and three terminal junctions. It is shown that, on the one hand, experimental devices of each type of the three nanoribbon-based structures have been reported, that promising performance of these devices has been demonstrated and/or predicted, and that in part they possess functionalities not attainable with conventional semiconductor devices. On the other hand, it is emphasized that -in spite of the remarkable progress achieved during the past 10 yearsgraphene nanoribbon devices still face a lot of problems and that their prospects for future applications remain unclear.

We report the formation of nanobubbles on graphene with a radius of the order of 1 nm, using ultralow energy implantation of noble gas ions (He, Ne, Ar) into graphene grown on a Pt(111) surface. We show that the universal scaling of the aspect ratio, which has previously been established for larger bubbles, breaks down when the bubble radius approaches 1 nm, resulting in much larger aspect ratios. Moreover, we observe that the bubble stability and aspect ratio depend on the substrate onto which the graphene is grown (bubbles are stable for Pt but not for Cu) and trapped element. We interpret these dependencies in terms of the atomic compressibility of the noble gas as well as of the adhesion energies between graphene, the substrate, and trapped atoms.

No abstract

A method to measure the reaction rates of the iron acceptor pair association and dissociation is presented and applied. The activation energies of the dissociation and association reaction are determined for the acceptors boron, aluminum, gallium and indium. Additionally, the activation energies are reported for different illumination intensities. It is found that the activation energy of the association reaction varies for the investigated acceptors and that the activation energy of the dissociation reaction depends strongly on the illumination intensity. It is shown that neglecting of the dissociation reaction in the evaluation of relative interstitial iron content decrease causes a considerable overestimation of the activation energy of the iron acceptor association.