Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms

Abstract

Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes.

Local Plasmon Engineering in Doped Graphene

“…Because of the ideal “gentle STEM” combination of ultrahigh vacuum conditions and low acceleration voltage (which minimizes any beam-induced damage to the samples), individual B , and N ,,, atom dopants in graphene can be identified directly in an ADF image. So-called “core” EEL spectra (EEL > ≈50 eV) contain information about the local electronic structure and bonding in graphene, ,,− while “valence” EEL spectra (EEL < ≈50 eV) contain information about the graphene dielectric response. ,,− In combination with simultaneous (STEM) ADF imaging, EEL spectra allow for a direct correlation of defect-induced modifications of the graphene electronic structure ,,− and dielectric response , with atomic scale structure. These capabilities mean STEM-EELS is an excellent technique for investigating the interband plasmon response induced by individual B and N atom dopants in graphene, as this information can be correlated directly with the atomic structure all within the same experiment.…”

Controlled Functionalisation of 2-D Materials for Quantum Device Development: assessment of Single Atom Behaviour via Atomic Resolution Electron Microscopy and Spectroscopy

“…Achievement of these is very likely, if nanoscale localised electronic doping compatible with large-scale integrated semiconductor technologies can be achieved. Targeted doping, of nano-tubes and 2-D materials, e.g., graphene and monolayer BN as well as transition metal dichalcogenides (TMDs), has been attempted here via ultra-low energy ion implantation in order to tailor bandstructure and thus opto-electronic properties [1,2,3,4]. TMDs are particularly promising for quantum device purposes, as they possess many unique properties, such as large direct bandgaps, optically addressable spin and valley pseudospin degrees of freedom and large magnetic moments.…”