How isolated atoms can be controlled with an electron beam

All matter consists of atoms. These are so tiny that you can only see them with modern equipment such as high precision electron microscopes. The same electrons that represent atomic structures in these devices can also be used to selectively move individual atoms in the material. This new technique, developed by researchers at the University of Vienna, now allows almost perfect control of the movement of individual silicon atoms in graphene. The latest research was published in the prestigious scientific journal "Nano Letters".

A notable breakthrough in nanotechnology, the tunneling microscope, has allowed atoms to move to surfaces since the late 1980s. Until recently, it was the only way to target individual atoms in a controlled manner. Now it is possible to focus on samples by means of scanning electron microscopes (STEM) with a high precision electron beam with subatomic accuracy. This allows scientists to directly image each atom in two-dimensional materials such as graphene and direct it with the electron beam. Every electron in this beam has a small chance of being scattered from the nucleus of this targeted atom, giving the atom a small push in the opposite direction.

Based on the results of research in recent years, a team of researchers Using the advice of Toma Susi, an ultra high performance Nion UltraSTEM 100 electron microscope is used to move single silicon atoms to graphene with an impressive atomic precision. Even with manual manipulation, this impressive technique is already able to perform these targeted movements at a speed comparable to all the other known precise techniques. "The precision we can achieve by controlling the electron beam by hand in any direction is remarkable, and we have now taken the first steps towards automation and are able to detect the movements in real time, "says Toma Susi. Overall, researchers performed nearly 300 controlled atomic jumps. In addition to the motion of an atom in one of the graphene hexes and new extended paths in the graphene grid, they could repeatedly move a silicon atom back and forth between two adjacent atomic positions distant from one to ten millionth of a meter. This can be considered as if you were moving an atomic switch. In principle, it can save one bit of information in the world's highest storage density. Toma Susi concludes: "It will take some time before having computers or mobile phones with atomic memory, but doping atoms like silicon in graphene have the potential to serve as bits – and this with a near density of the physically possible limit. " [19659003] The work was made possible by funding from the European Research Council (ERC) and the Scientific Research Fund (FWF).

Publication in "Nano Letters":
Electron Beam Manipulation of Silicon Dopants in Graphene: Mukesh Tripathi, Andreas Mittelberger, Nicholas Pike, Clemens Mangler, Jannik C. Meyer, Matthew Verstraete, Jani Kotakoski and Toma Susi. Nano Letters Article as soon as possible,
DOI: 10.1021 / acs.nanolett.8b02406.

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