AVS 63rd International Symposium & Exhibition
    Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic Tuesday Sessions
       Session SA+2D+AC+AS+TF-TuM

Invited Paper SA+2D+AC+AS+TF-TuM3
Advanced Spectro-microscopy of Ion Irradiated Graphene-metal Interfaces: From Substitutional Implantation to Nanobubble Formation

Tuesday, November 8, 2016, 8:40 am, Room 103C

Session: Applications of Synchrotron-based Techniques to 2D Materials (8:00-10:00 am)/Complex Functional Materials and Heterostructures (11:00 am-12:20 pm)
Presenter: Andrea Locatelli, Elettra - Sincrotrone Trieste, Italy
Authors: A. Locatelli, Elettra - Sincrotrone Trieste, Italy
A. Sala, Elettra - Sincrotrone Trieste, Italy
T.-O. Menteş, Elettra - Sincrotrone Trieste, Italy
G. Zamborlini, Peter Grünberg Institute (PGI-6) Jülich
L. Patera, IOM-CNR Laboratorio TASC, Italy
C. Africh, IOM-CNR Laboratorio TASC, Italy
M. Imam, Abdus Salam International Centre for Theoretical Physics, Italy
N. Stojić, Abdus Salam International Centre for Theoretical Physics, Italy
N. Binggeli, Abdus Salam International Centre for Theoretical Physics, Italy
Correspondent: Click to Email
The exploitation of graphene in the next generation electronics depends on our ability of preserving and tailoring its unique electronic and transport properties. Whereas the preservation of the free-standing characteristics of graphene demands to decouple the film from its support, their modification requires functionalization and thus chemical doping. Varied methods have been devised to implant exospecies into and under the C lattice mesh. Among them, irradiation of nitrogen ions has emerged as one of the most powerful approaches, producing enhanced physical and chemical properties rather than detrimental effects. At variance with other methods, ion irradiation enables implementation of lithographic approaches for doping graphene, a feature which is most desirable for creating arrays of devices.

The characterization of complex and laterally-heterogeneous interfaces, such as that of ion-irradiated graphene, demands advanced microscopy tools. Here, we will demonstrate the present capabilities of cathode lens spectro-microscopy. As a first example, we report a proof of principle experiment demonstrating that low energy ion irradiation through an aperture can be used to achieve local control on doping in graphene. Our study tackles the fabrication of a 2-dimensional heterojunction between n-doped and almost neutral single-layer graphene on Ir(111). Here, XPEEM is employed to characterize the transition region between areas with metallic and semimetal-like density of states and its thermal stability [1].

Then, we will focus on the irradiation of graphene with low energy Ar and Ne ions, reporting on the formation of nanobubbles upon annealing. The morphology and local stoichiometry of the Ar-ion irradiated interface were characterized by LEEM, XPEEM and STM, specifically addressing the thermal stability of noble gas nanobubbles. These structures display a lateral size up to tens of nanometers and height of several atomic layers. Remarkably, the Ar clusters remain trapped under graphene up to temperatures nearing 1100°C, suffering no material loss through the mesh or its edges. Ab-initio calculations demonstrate that intercalated Ar undergoes extreme pressures, up to few tens GPa. The nanobubble ripening process turns out to be driven by the minimization of the energy cost of film distortion and loss of adhesion [2]. The electronic properties of the ion irradiated interface will be also discussed.

[1] A. Sala, G. Zamborlini, T.O. Menteş, A. Locatelli; Small 11(44), 5927–5931(2016).

[2] G. Zamborlini, M. Imam , L.L. Patera , T.O. Menteş , N. Stojić , C.Africh , A. Sala , N. Binggeli , G. Comelli and A.Locatelli; Nano Lett. 15(9), 6162–6169 (2015).