A research team has created a new method to capture the ultrafast motion of atoms inside tiny switches that control the flow of current in electronic circuits. Pictured here are Aditya Sood (left) and Aaron Lindenberg (right). Credit: Greg Stewart/SLAC National Accelerator Laboratory
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Scientists Take First Shot of Ultrafast Switching in Quantum Electronics
They discovered a short-lived state that could result in faster and more energy efficient computing devices.
Electronic circuits that calculate and store information contain millions of tiny switches that control the flow of electric current. A deeper understanding of how these tiny switches work could help researchers push the boundaries of modern computing.
Now scientists have created the first snapshots of the atoms moving inside one of those switches when it is turned on and off. Among other things, they discovered short-lived states within switches that might someday be exploited for faster, more energy-efficient computing devices.
The research team from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, Hewlett Packard Lab, Penn State University and Purdue University describe their work in a paper published in Science today (15 July 2021).
“This research is a breakthrough in ultrafast technology and science,” said Xijie Wang, scientist and SLAC collaborator. “This marks the first time that researchers have used ultrafast electron diffraction, which can detect the motion of tiny atoms in a material by scattering a strong electron beam from a sample, to observe an electronic device in operation.”
The team used electrical pulses, shown here in blue, to turn the custom-made switch on and off several times. They timed these electrical pulses to arrive just before the electron pulses generated by the SLAC MeV-UED ultrafast electron diffraction source, which captures the atomic motions that occur within these switches as they are turned on and off. Credit: Greg Stewart/SLAC National Accelerator Laboratory
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Catch cycle
For this experiment, the team’s specially designed mini electronic switch made of vanadium dioxide, a prototypical quantum material whose ability to switch back and forth between insulating and conducting states of electricity near room temperature could be utilized as a switch for future computing. This material also has applications in brain-inspired computing due to its ability to create electronic pulses that mimic nerve impulses fired in the human brain.
The researchers used electrical pulses to activate this switch back and forth between insulating and conducting states while taking photos showing subtle changes in their atomic arrangement over a millionth of a second. The photos, taken with SLAC’s ultrafast electron diffraction camera, MeV-UED, were strung together to create a molecular film of atomic motion.
Lead researcher Aditya Sood discusses new research that could lead to a better understanding of how tiny switches inside electronic circuits work. Credit: Olivier Bonin National Accelerator Laboratory/SLAC
“This ultrafast camera can actually see into a material and take a snapshot of how its atoms move in response to a sharp pulse of electrical excitation,” said collaborator Aaron Lindenberg, an investigator at the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. and a professor in the Department of Materials Science and Engineering at Stanford University. “At the same time, it also measures how the electronic properties of the material change over time.”
With this camera, the team discovered new intermediate states in matter. It is created when a material responds to an electrical pulse by switching from an insulating to a conducting state.
“Insulating states and conductors have slightly different arrangements of atoms, and it usually takes energy to move from one to another,” said scientist and SLAC collaborator Xiaozhe Shen. “But when a transition occurs through this transition state, the transition can occur without any change in the arrangement of the atoms.”
Opens a window on atomic motion
Although the intermediate state is only a few millionths of a second, it is stabilized by defects in the material.
To follow up on this research, the team is investigating how to engineer this material defect to make this new state more stable and durable. This will allow them to build devices in which electronic switching can occur without atomic motion, which will operate faster and require less energy.
“The results demonstrate the robustness of electrical switching over millions of cycles and identify possible switching speed limits for such devices,” said collaborator Shriram Ramanathan, a professor at Purdue. “This research provides invaluable data on microscopic phenomena occurring during device operation, which are critical for designing future circuit models.”
The research also offers a new way to synthesize materials that do not exist under natural conditions, allowing scientists to observe them on very fast timescales and then potentially adjust their properties.
“This method gives us a new way to see the device as it functions, opening a window to see how atoms move,” said lead author and SIMES researcher Aditya Sood. “It is very interesting to bring together ideas from the traditionally different fields of electrical engineering and ultrafast science. Our approach will enable the creation of the next generation of electronic devices that can meet the world’s evolving needs for intelligent and data-intensive computing.”
The MeV-UED is an LCLS user facility instrument, operated by SLAC on behalf of the DOE Office of Science, which funded this research.
SLAC is a dynamic multiprogrammed laboratory that explores the workings of the universe at the largest, smallest, and fastest scales, and creates powerful tools used by scientists around the world. With research spanning particle physics, astrophysics and cosmology, materials, chemistry, bio and energy sciences, and scientific computing, we help solve real-world problems and advance the interests of nations.
SLAC is operated by Stanford University for the US Department of Energy’s Office of Science. The Office of Science is the single largest proponent of basic research in the physical sciences in the United States and works to address some of the most pressing challenges of our time.
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