Abstract
The direct manipulation of individual atoms in materials using scanning probe microscopy has been a seminal achievement of nanotechnology. Recent advances in imaging resolution and sample stability have made scanning transmission electron microscopy a promising alternative for single-atom manipulation of covalently bound materials. Pioneering experiments using an atomically focused electron beam have demonstrated the directed movement of silicon atoms over a handful of sites within the graphene lattice. Here, we achieve a much greater degree of control, allowing us to precisely move silicon impurities along an extended path, circulating a single hexagon, or back and forth between the two graphene sublattices. Even with manual operation, our manipulation rate is already comparable to the state-of-the-art in any atomically precise technique. We further explore the influence of electron energy on the manipulation rate, supported by improved theoretical modeling taking into account the vibrations of atoms near the impurities, and implement feedback to detect manipulation events in real time. In addition to atomic-level engineering of its structure and properties, graphene also provides an excellent platform for refining the accuracy of quantitative models and for the development of automated manipulation.
Highlights
Single-atom manipulation using scanning probe microscopy was established already 25 years ago,[1,2] it continues to provide impressive technological advances, such as atomic memory arrays,[3] as well as insight into physical phenomena including quantum many-body effects.[4,5] only relatively weakly bound surface atoms far below room temperature can typically[6] be affected due to the limited interaction energy with the atomically sharp tip
First-principles simulations revealed the mechanism of Si C bond inversions: each electron has a finite chance to transfer just enough out-of-plane kinetic energy to one C neighbor to cause it to exchange places with the Si,[11] a rare example of a direct exchange diffusion in a crystalline material.[12]
The movement was not controlled, but it was clear that this should be possible by purposefully directing the electron irradiation at the desired C neighbor.[11,13]
Summary
Overviews where the segmented line indicates each of the 34 precisely directed lattice jumps and dots the locations of the Si atom in each previous panel (I−VI). (b) Schematic illustration of the path with orange circles indicating the position of the Si in each overview labeled with Roman numerals (I−VI) and with Arabic numerals indicating the number of 10 s spot irradiations required for each jump. (c) Closer views before and after the first jump. At 55 keV, we repeated the latter two kinds of experiments, observing very few double jumps due to the implemented feedback and collecting further statistical data on the required doses for our theoretical analyses As shown by these examples, our level of control is sufficient for creating extended structures[19] once the density of impurities can be Figure 2. Figures S1−S4: EELS spectrum of a Si substitution, MAADF detector feedback time series, example manipulation sequence at 55 keV, and the calculated out-of-plane mean-square velocities of the graphene supercell with a Si impurity (electron microscopy images are provided as open data in Ref. 42) (PDF).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
