title: Ion-beam modification of 2-D materials - single implant atom analysis via annular dark-field electron microscopy.
abstract: Functionalisation of two-dimensional (2-D) materials via low energy ion implantation could open possibilities for fabrication of devices based on such materials. Nanoscale patterning and/or electronically doping can thus be achieved, compatible with large scale integrated semiconductor technologies. Using atomic resolution High Angle Annular Dark Field (HAADF) scanning transmission electron microscopy supported by image simulation, we show that sites and chemical nature of individual implants/ dopants in graphene, as well as impurities in hBN, can uniquely and directly be identified on grounds of their position and their image intensity in accordance with predictions from Z-contrast theories. Dopants in graphene (e.g., N) are predominantly substitutional. In other 2-Ds, e.g. dichalcogenides, the situation is more complicated since implants can be embedded in different layers and substitute for different elements. Possible configurations of Se-implants in MoS2are discussed and image contrast calculations performed. Implants substituting for S in the top or bottom layer can undoubtedly be identified. We show, for the first time, using HAADF contrast measurement that successful Se-integration into MoS2can be achieved via ion implantation, and we demonstrate the possibility of HAADF image contrast measurements for identifying impurities and dopants introduced into in 2-Ds.
authors.affiliation: Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick, Ireland. Electronic address: Ursel.Bangert@ul.ie.
authors.forename: U
authors.initials: U
authors.lastname: Bangert
authors.affiliation: Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick, Ireland.
authors.forename: A
authors.initials: A
authors.lastname: Stewart
authors.affiliation: Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick, Ireland.
authors.forename: E
authors.initials: E
authors.lastname: O'Connell
authors.affiliation: Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick, Ireland.
authors.forename: E
authors.initials: E
authors.lastname: Courtney
authors.affiliation: SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury WA4 4AD, United Kingdom.
authors.forename: Q
authors.initials: Q
authors.lastname: Ramasse
authors.affiliation: SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury WA4 4AD, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Kepaptsoglou
authors.affiliation: II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-PLatz 1, 37077 Göttingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Hofsäss
authors.affiliation: II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-PLatz 1, 37077 Göttingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Amani
authors.affiliation: Peter Grünberg Institut 9, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: J-S
authors.initials: JS
authors.lastname: Tu
authors.affiliation: Peter Grünberg Institut 9, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Kardynal
keywords: 2-D materials; HAADF STEM imaging; Ion implantation; MoS(2); Z-contrast