Research Bits: July 18

Miniaturized ferroelectric FETs

Researchers from the University of Pennsylvania, Hanyang University, King Abdulaziz University, King Abdullah University of Science and Technology, and University of Tokyo proposed a new ferroelectric FET (FE-FET) design with improved performance for both computing and memory.

The transistor layers the two-dimensional semiconductor molybdenum disulfide (MoS2) on top of the ferroelectric material aluminum scandium nitride (AlScN), demonstrating that the two materials can be effectively combined to create transistors that can be manufactured in large arrays scalable to industrial platforms.

“Because we have made these devices combining a ferroelectric insulator material with a 2D semiconductor, both are very energy efficient,” said Deep Jariwala, associate professor in the Department of Electrical and Systems Engineering at the University of Pennsylvania. “You can use them for computing as well as memory — interchangeably and with high efficiency.”

Researchers at the University of Pennsylvania School of Engineering and Applied Science have introduced a new FE-FET design that demonstrates record-breaking performances in both computing and memory. (Credit: University of Pennsylvania)

“With our semiconductor, MoS2, at a mere 0.7 nanometers, we weren’t sure it could survive the amount of charge that our ferroelectric material, AlScN, would inject into it,” said Kwan-Ho Kim, a Ph.D. candidate at the University of Pennsylvania. “To our surprise, not only did both of them survive, but the amount of current this enables the semiconductor to carry was also record-breaking.”

Next, the team plans to work on further miniaturization to produce devices that operate with voltages low enough to be compatible with leading-edge consumer device manufacturing.

Kim, KH., Oh, S., Fiagbenu, M.M.A. et al. Scalable CMOS back-end-of-line-compatible AlScN/two-dimensional channel ferroelectric field-effect transistors. Nat. Nanotechnol. (2023). https://doi.org/10.1038/s41565-023-01399-y

Building topological semimetals

Researchers at the University of Minnesota Twin Cities synthesized thin films of topological semimetal materials they believe have the potential to generate more computing power and memory storage while using significantly less energy.

“This research shows for the first time that you can transition from a weak topological insulator to a topological semimetal using a magnetic doping strategy,” said Jian-Ping Wang, professor and chair in the University of Minnesota Department of Electrical and Computer Engineering. “We’re looking for ways to extend the lifetimes for our electrical devices and at the same time lower the energy consumption, and we’re trying to do that in non-traditional, out-of-the-box ways.”

The Pt₃Sn and Pt₃Sn_xFe_1-x thin films were created using an industry-compatible sputtering process. With robust quadratic and linear negative longitudinal magnetoresistance features, they could potentially be used in development of advanced spin-orbit torque spintronic devices.

“Normally, when you apply a magnetic field, the longitudinal resistance of a material will increase, but in this particular topological material, we have predicted that it would decrease. We were able to corroborate our theory to the measured transport data and confirm that there is indeed a negative resistance,” said Tony Low, an associate professor in the University of Minnesota Department of Electrical and Computer Engineering.

Zhang, D., Jiang, W., Yun, H. et al. Robust negative longitudinal magnetoresistance and spin–orbit torque in sputtered Pt3Sn and Pt3SnxFe1-x topological semimetal. Nat Commun 14, 4151 (2023). https://doi.org/10.1038/s41467-023-39408-2

DNA digital camera

Researchers from the National University of Singapore propose a way to make DNA data storage commercially scalable.

In contrast to many current approaches, which focus on synthesizing DNA strands outside the cells, the team used live cells, which contain an abundance of DNA that can act as a ‘data bank,’ circumventing the need to synthesize the genetic material externally. The researcher’s approach, called BacCam, combines various biological and digital techniques to emulate a digital camera’s functions using biological components.

“Imagine the DNA within a cell as an undeveloped photographic film,” explained Poh Chueh Loo, an associate professor in the College of Design and Engineering at the National University of Singapore. “Using optogenetics – a technique that controls the activity of cells with light akin to the shutter mechanism of a camera, we managed to capture ‘images’ by imprinting light signals onto the DNA ‘film’.”

Next, using barcoding techniques similar to photo labelling, the researchers marked the captured images for unique identification. Machine learning algorithms were employed to organize, sort, and reconstruct the stored images.

The method was able to capture and store multiple images simultaneously using different light colors. The team also says it is easily reproducible and scalable.

“Our method represents a major milestone in integrating biological systems with digital devices,” said Poh. “By harnessing the power of DNA and optogenetic circuits, we have created the first ‘living digital camera,’ which offers a cost-effective and efficient approach to DNA data storage. Our work not only explores further applications of DNA data storage but also re-engineers existing data-capture technologies into a biological framework. We hope this will lay the groundwork for continued innovation in recording and storing information.”

Lim, C.K., Yeoh, J.W., Kunartama, A.A. et al. A biological camera that captures and stores images directly into DNA. Nat Commun 14, 3921 (2023). https://doi.org/10.1038/s41467-023-38876-w