Modulation acceptor doping; uncovering atomic behavior; SiC power module.
Researchers from TU Wien, Johannes Kepler University Linz, and TU Bergakademie Freiberg manufactured a silicon-germanium (SiGe) transistor using an alternative approach that involves doping the insulating oxide layer to produce a long-range effect that extends into the semiconductor.
Called modulation acceptor doping (MAD), the technique enables the doped oxide layer to improve the conductivity of the SiGe semiconductor without altering the crystal itself. “We were able to show that MAD technology has over 4000 times higher conductivity, improved switch-on behaviour and lower energy consumption. This could pave the way for a new generation of versatile nanotransistors,” said Masiar Sistani, a postdoctoral researcher at TU Wien’s Institute for Solid State Electronics, in a press release.
Sistani highlighted the approach’s potential for building cryogenic control and read-out electronics in quantum computers: “Conventional transistors have to work in very close proximity to ultra-cold quantum components. This is where conventional doping technology often fails – this is referred to as ‘freezing out’ of the charge carriers. Our technology circumvents these problems. The doping of the oxide layer remains effective even at extremely low temperatures.” [1]
Researchers from Lawrence Berkeley National Laboratory, George Washington University, University of Arkansas, and Dartmouth College discovered that atoms in semiconductors will arrange themselves in distinctive localized patterns that change the material’s band gap.
“We’re going to be able to really push the boundaries beyond current capabilities by designing semiconductors at the atomic scale,” said Lilian Vogl, group leader of the Environmental & Analytical Electron Microscopy Group at the Max Planck Institute for Sustainable Materials, in a statement. “We are opening the door to a new era of information technology at the atomic scale, unlocking the deterministic placement of SRO [short-range order] motifs for tailoring of band structures that could impact a wide variety of technologies, from topological quantum materials to neuromorphic computing to optical detectors.”
To investigate the possibility of short-range order (SRO) in semiconductors, the team studied germanium containing a small amount of tin and silicon using an electron microscopy technique called 4D-STEM equipped with an energy-filtering device to improve contrast. A pre-trained neural network was used to sort the diffraction images and identify six recurring motifs representing particular atomic arrangements in the sample material.
Machine learning was then used to model millions of atoms in the material’s structure and perform simulated 4D-STEM on different possible structural arrangements until matches were found for the motifs in the experimental data.
“It’s remarkable that modeling and experiment can work seamlessly to unravel SRO structural motifs for the first time,” said Tianshu Li, a professor of civil and environmental engineering at George Washington University, in a statement. “Proving SRO experimentally is not an easy task, let alone identifying its structural motifs. Signals from SRO can easily be obscured by defects or inherent movement of atoms at room temperature, and until now there was no clear way to separate them. This work represents the first step toward our broader goal.” [2]
Researchers from the National Renewable Energy Laboratory built a low-cost, efficient silicon-carbide-based power module capable of supporting data centers, power grids, microreactors, eVTOL aircraft, and military vehicles.
The team states that the 1200-volt, 400-amp Ultra-Low Inductance Smart (ULIS) power module is capable of achieving five times greater energy density than predecessor designs in a smaller package, with parasitic inductance seven to nine times lower than current state-of-the-art SiC power modules.
The module uses a disc-like shape that enables more devices to be housed in a smaller area, accompanied by novel current routing that allows for maximum magnetic flux cancellation and low-loss electrical output.
“Our biggest concern was that the device switches off and on very quickly, and we needed a layout that wouldn’t create a chokepoint within the design,” said Shuofeng Zhao, an NREL power electronics researcher, in a release. “We squished it flat, like a pancake, and suddenly we had a low-cost, high-performing design that was much easier to fabricate.”
Instead of a ceramic base, ULIS uses a flexible polymer that bonds to copper using just pressure and heat, making it inexpensive to fabricate. It can also function as an isolated, modular unit that can be controlled and monitored using a low-latency wireless communication protocol.
[1] A. Fuchsberger, K. Eysin, L. Wind, et al. “Modulation-Acceptor-Doped SiGe Schottky Barrier Field-Effect Transistors,” IEEE Electron Device Letters, vol. 46, no. 8, pp. 1429-1432, Aug. 2025. https://dx.doi.org/10.1109/led.2025.3577243
[2] L. M. Vogl, S. Chen, P. Schweizer, et al. Identification of short-range ordering motifs in semiconductors. Science 389,1342-1346 (2025). https://doi.org/10.1126/science.adu0719
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