‘Writing’ With Atoms Could Transform Materials Fabrication for Quantum Devices
By using an electron beam, or e-beam, to remove and deposit the atoms, the ORNL scientists could accomplish a direct writing procedure at the atomic level.
“With these papers, we are redirecting what atomic-scale fabrication will look like using electron beams,” Dyck says. “Together, these manuscripts outline what we believe will be the direction atomic fabrication technology will take in the near future and the change in conceptualization that is needed to advance the field.”
To demonstrate the method, the researchers moved an e-beam back and forth over a graphene lattice, creating minuscule holes. They inserted tin atoms into those holes and achieved a continuous, atom-by-atom, direct writing process, thereby populating the exact same places where the carbon atom had been with tin atoms.
“The process is remarkably intuitive,” says ORNL’s Andrew Lupini, STEM group leader and a member of the research team. “STEMs work by transmitting a high-energy e-beam through a material. The e-beam is focused to a point smaller than the distance between atoms and scans across the material to create an image with atomic resolution. However, STEMs are notorious for damaging the very materials they are imaging.”
“We believe that atomic-scale synthesis processes could become a matter of routine using relatively simple strategies. When coupled with automated beam control and AI-driven analysis and discovery, the synthescope concept offers a window into atomic synthesis processes and a unique approach to atomic-scale manufacturing,” Jesse says.
This artistic rendering shows a way to make materials atom by atom. The electron beam ejects a carbon atom from graphene, and a different atom bonds at the vacancy. Credit: Ondrej Dyck/ ORNL, U.S. Department of Energy
Such devices might include quantum computers—a proposed next generation of computers that may vastly outpace today’s fastest supercomputers, quantum sensors, and quantum communication devices that require a source of a single photon to create a secure quantum communications system.
The scientists, who are part of the CNMS, a nanoscience research center and DOE Office of Science user facility, detailed their research and their vision in a series of four papers in scientific journals over the course of a year, starting with proof of principle that the synthescope could be realized. They have applied for a patent on the technology.
The scientists realized they could exploit this destructive “bug” and instead use it as a constructive feature and create holes on purpose. Then they could put whatever atom they want in that hole, exactly where they made the defect. By purposely damaging the material, they create a new material with different and useful properties.
That’s important because the ability to tailor materials atom by atom can be applied to many future technological applications in quantum information science, and more broadly in microelectronics and catalysis, and for gaining a deeper understanding of materials synthesis processes. This work could facilitate atomic-scale manufacturing, which is notoriously challenging.
To accomplish improved control over atoms, the research team created a tool they call a synthescope for combining synthesis with advanced microscopy. The researchers used a scanning transmission electron microscope, or STEM, transformed into an atomic-scale material manipulation platform. The synthescope will advance the state of the art in fabrication down to the level of the individual building blocks of materials. This new approach allows researchers to place different atoms into a material at specific locations; the new atoms and their locations can be selected to give the material new properties.
“Simply by the fact that we can now start putting atoms where we want, we can think about creating arrays of atoms that are precisely positioned close enough together that they can entangle, and therefore share their quantum properties, which is key to making quantum devices more powerful than conventional ones,” Dyck says.
A conceptual drawing shows a heater platform designed to deliver atomized material to a sample, converting a scanning transmission electron microscope into a synthescope. Credit: Ondrej Dyck/ORNL, U.S. Department of Energy
The research was funded by the U.S. Department of Energy’s Office of Science.
“By working at the atomic scale, we also work at the scale where quantum properties naturally emerge and persist,” says Stephen Jesse, a materials scientist who leads this research and heads the Nanomaterials Characterizations section at ORNL’s Center for Nanophase Materials Sciences, or CNMS. “We aim to use this improved access to quantum behavior as a foundation for future devices that rely on uniquely quantum phenomena, like entanglement, for improving computers, creating more secure communications, and enhancing the sensitivity of detectors.”
“One strategy to tackle these challenges is to build and operate at the scale where quantum mechanics exist more naturally—at the atomic scale,” Dyck says. “We realized that if we have a microscope that can resolve atoms, we may be able to use the same microscope to move atoms or alter materials with atomic precision. We also want to be able to add atoms to the structures we create, so we need a supply of atoms. The idea morphed into an atomic-scale synthesis platform—the synthescope.”
An artistic rendering depicts direct writing using ORNL’s synthescope, a novel microscopy technique, to continuously insert tin atoms into graphene, opening possibilities for materials fabrication atom by atom. Credit: Ondrej Dyck/ORNL, U.S. Department of Energy
“Classic computers use bits, which can be either 0 or 1, and do calculations by flipping these bits,” says ORNL’s Ondrej Dyck, a materials scientist contributing to the research. “Quantum computers use qubits, which can be both 0 and 1 at the same time. The qubits can also become entangled, with one qubit connected to the state of another. This entangled system of qubits can be used to solve certain problems much faster than classic computers. The tricky part is keeping these delicate qubits stable and working correctly in the real world.
A heater platform was designed to deliver atomized material to a sample, converting a scanning transmission electron microscope into a synthescope. Credit: Ondrej Dyck/ORNL, U.S. Department of Energy
“We are not just moving atoms around,” Jesse says. “We show that we can add a variety of atoms to a material that were not previously there and put them where we want them. Currently there is no technology that allows you to place different elements exactly where you want to place them and have the right bonding and structure. With this technology, we could build structures from the atom up, designed for their electronic, optical, chemical, or structural properties.”
“We’re exploring methods to create these defects on demand so we can place them where we want to,” Jesse says. “Since STEMs have atomic-scale imaging capabilities, and we work with very thin materials that are only a few atoms in thickness, we can see every atom. So, we are manipulating matter at the atomic scale in real time. That’s the goal, and we are actually achieving it.”
(ORNL: Oak Ridge, TN) — A new technology to continuously place individual atoms exactly where they are needed could lead to new materials for devices that address critical needs for the field of quantum computing and communication that can’t be produced by conventional means, say scientists who developed it.