Cornell researchers have made a semiconductor with a bandgap greater than 7 electron volts, clearing a materials barrier that could eventually help electronics handle higher voltages and temperatures.
The silicon-doped aluminum gallium oxide surpassed the previous benchmark of about 6 electron volts, according to Cornell's account of work published Oct. 7 in Nature.
A bandgap is the energy needed to free electrons so they can carry current. A wider gap can allow a semiconductor to withstand stronger electric fields, but finding a material that also conducts electricity well has been a central challenge.
Jacob Steele, a Cornell doctoral student and the study's lead author, grew thin films using suboxide molecular beam epitaxy. The lower-temperature growth process made it possible to incorporate silicon in a way that supplied mobile electrons rather than leaving the material effectively insulating.
At room temperature, the films conducted electricity more than 100 million times better than previously reported materials with bandgaps above 6 electron volts, Cornell said.
That combination matters because a material must both withstand voltage and carry current to function in power electronics. A wide bandgap alone does not make a useful switching device.
Darrell Schlom, a professor in Cornell's Duffield College of Engineering and a senior author of the research, worked with colleagues across materials science and electrical engineering on the project.
Researchers led by Huili Grace Xing and Debdeep Jena used the material to demonstrate a working diode and a transistor called an AlphaFET. Co-lead author Debaditya Bhattacharya designed, fabricated and measured the devices.
The transistor's gate changed its current by more than four orders of magnitude, demonstrating that the material could be controlled electronically. The researchers also grew the films on sapphire, an available substrate that could provide a route toward larger-scale production.
Potential applications include the equipment that converts and controls electricity in electric vehicles, power grids, data centers and electric propulsion systems. The material also could have uses in photonics, Cornell said.
Those possibilities remain development goals. The experimental devices do not establish that the material is ready for commercial products.
Microscopy work by David Muller and Naomi Pieczulewski, who earned her doctorate in 2026, found substantial defects in the films. Understanding and reducing those defects is part of the work needed to improve performance.
The research drew support from the Air Force Research Laboratory-Cornell Center for Epitaxial Solutions. Researchers also used the National Science Foundation-supported Cornell NanoScale Science and Technology Facility and PARADIM, along with Cornell Center for Materials Research facilities.
The study is available in Nature, and Cornell's report describes the fabrication process and experimental devices.
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