| AVS 65th International Symposium & Exhibition | |
| Extending Additive Manufacturing to the Atomic Scale Focus Topic | Wednesday Sessions |
| Session AM+NS+SS-WeM |
| Session: | Nanofabrication with Focused Electron Beams (8:00-10:00 am)/Atomic Scale Manipulation with Focused Electron Beams (11:00 am-12:20 pm) |
| Presenter: | Demie Kepaptsoglou, SuperSTEM Laboratory, UK |
| Authors: | D. Kepaptsoglou, SuperSTEM Laboratory, UK F. Hage, SuperSTEM Laboratory, UK T. Susi, University of Vienna, Austria J. Kotakoski, University of Vienna, Austria J. Meyer, University of Vienna, Austria Y.C. Lin, National Institute of Advanced Industrial Science and Technology (AIST), Japan K. Suenaga, National Institute of Advanced Industrial Science and Technology (AIST), Japan T. Hardcastle, University of Leeds, UK U. Bangert, University of Limerick, Republic of Ireland JA. Amani, University of Göttingen, Germany H. Hofsaess, University of Göttingen, Germany Q. Ramasse, SuperSTEM Laboratory, UK, United Kingdom of Great Britain and Northern Ireland |
| Correspondent: | Click to Email |
The past decade has seen incredible progress in the ability to isolate and manipulate two-dimensional crystals. Due to their unique structure and dimensionality, it is possible to confine charge carriers in two dimensions, resulting in peculiar physical, chemical and electronic properties. Such novel properties can be further controlled and tuned through defects such as single atom dopants, interfaces, etc. This defect engineering takes place quite literally at the atomic level, where a combination of low voltage scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS) and ab-initio calculations provides not only the most powerful means of characterization, but also a unique tool for manipulating the single atom structures and engineer their electronic interaction with the host matrix. This approach was recently used to demonstrate that low energy ion implantation (of dopants such as N and B) can be successfully implemented to introduce single substitutional defects with excellent retention rates and without affecting the structural integrity of the surrounding graphene matrix. Atomically-resolved EELS experimental data reveals the bonding signature of the dopants themselves and their impact on the surrounding lattice. Ab initio calculations, in excellent agreement with the experiment, confirm the nature of the excited states being probed by the EELS experiments and the electronic structure reconfiguration of the doped material around the single atom dopants. Results directly confirm the possibility of tailoring the plasmonic properties of graphene in the ultraviolet waveband at the atomic scale, a crucial step in the quest for utilizing it’s properties toward the development of plasmonic and optoelectronic devices. The gentle STEM observation conditions can also be used to controllably drive the diffusion of substitutional dopants through single layer graphene, one atomic jump at a time. Atomically precise manipulation with STEM relies on recent advances in instrumentation that have improved the instruments’ stability and their beam positioning abilities. While momentum transfer from highly energetic electrons often leads to atom ejection, interesting dynamics can be induced when the transferable kinetic energies are comparable to bond strengths in the material. For instance, a combined experimental and theoretical study revealed that for Si dopants manipulated in the STEM by 60keV electrons these jumps are not due to impacts on the Si atom, but to sub-threshold impact events on the surrounding C atoms. This approach suggests that STEM could emerge as an alternative method for the direct assembly of nanostructures.