Electron‐Beam Manipulation of Silicon Impurities in Single‐Walled Carbon Nanotubes

Abstract

The recent discovery that impurity atoms in crystals can be manipulated with focused electron irradiation has opened novel perspectives for top-down atomic engineering. These achievements have been enabled by advances in electron optics and microscope stability, but also in the preparation of suitable materials with impurity elements incorporated via ion and electron-beam irradiation or chemical means. Here it is shown that silicon heteroatoms introduced via plasma irradiation into the lattice of single-walled carbon nanotubes (SWCNTs) can be manipulated using a focused 55-60 keV electron probe aimed at neighboring carbon sites. Moving the silicon atom mainly along the longitudinal axis of large 2.7 nm diameter tubes, more than 90 controlled lattice jumps were recorded and the relevant displacement cross sections estimated. Molecular dynamics simulations show that even in 2 nm SWCNTs the threshold energies for out-of-plane dynamics are different than in graphene, and depend on the orientation of the silicon-carbon bond with respect to the electron beam as well as the local bonding of the displaced carbon atom and its neighbors.Atomic-level engineering of SWCNTs where the electron wave functions are more strictly confined than in two-dimensional materials may enable the fabrication of tunable electronic resonators and other devices. 1 arXiv:1902.03972v1 [cond-mat.mtrl-sci]

Mesoporous Single-Atom-Doped Graphene–Carbon Nanotube Hybrid: Synthesis and Tunable Electrocatalytic Activity for Oxygen Evolution and Reduction Reactions

“…54−58 Here, both annular detectors were used, and elemental identification at the atomic resolution was conducted by EELS as has been previously done for heteroatom-doped graphene and CNTs. 54,55,59,60 Figure 2c,d demonstrates how the CNTs bridge the graphene nanoflakes, leading to the expected improvement in the material conductivity. Metallic Co and Mo atoms were not detected in the monolayer graphene (Figure 2e,f), whereas N was identified directly from the STEM image, for which the corresponding EELS point spectrum is shown in Figure S1.…”

“…In MAADF and especially HAADF imaging, the contrast of the image is highly sensitive to the atomic number or the mass of nuclei ( Z -contrast images). Z -contrast allows individual heavy atoms and small metallic nanoparticles to be distinguished from the low- Z carbon support based on their brightness. − Here, both annular detectors were used, and elemental identification at the atomic resolution was conducted by EELS as has been previously done for heteroatom-doped graphene and CNTs. ,,, Figure c,d demonstrates how the CNTs bridge the graphene nanoflakes, leading to the expected improvement in the material conductivity. Metallic Co and Mo atoms were not detected in the monolayer graphene (Figure e,f), whereas N was identified directly from the STEM image, for which the corresponding EELS point spectrum is shown in Figure S1.…”

Mechanism of Electron-Beam Manipulation of Single-Dopant Atoms in Silicon

“…Despite some advances, dopant placement remains the major hurdle for further progress. Electron-beam manipulation of covalently bound lattice impurities was recently proposed as a new kind of atomically precise manipulation tool. , Initially, this was limited to impurities in carbon nanomaterials including graphene − and single-walled carbon nanotubes, but a similar capability was recently also demonstrated for heavy Bi dopants in silicon. , However, the atomistic mechanism for their movement within the crystal was neither clear nor was it known whether other dopants could be affected, which beam energies are optimal, or whether the surrounding lattice is irreparably damaged.…”

Mechanism of electron-beam manipulation of single dopant atoms in silicon

“…Electron-beam manipulation of covalently bound lattice impurities was recently proposed as a new kind of atomically precise manipulation tool. 14,15 Initially, this was limited to impurities in carbon nanomaterials including graphene [16][17][18][19] and single-walled carbon nanotubes, 20 but a similar capability was recently also demonstrated for heavy Bi dopants in silicon. 21,22 However, the atomistic mechanism for their movement within the crystal was not clear, nor was it known whether other dopants could be affected, which beam energies are optimal, nor whether the surrounding lattice is irreparably damaged.…”