World’s widest-bandgap semiconductor built into working transistor for first time

Representative image showing a robotic arm handling a semiconductor chip.Getty ImagesKey TakeawaysUS scientists developed a record-breaking semiconductor with a bandgap exceeding seven eV.It could improve energy efficiency in electric vehicles, aircraft, and power grids.The team achieved over 100 million times higher conductivity than previously reported materials in the same bandgap category. A new semiconductor developed by US researchers reportedly boasts the world’s widest bandgap of more than seven electron volts (eV), and could lead to more efficient electric vehicles (EVs), power grids, and data centers. The material was created by engineers at New York’s Cornell University. It is made from silicon-doped aluminum gallium oxide grown on sapphire. In addition, it has the widest bandgap reported for a semiconductor in working electronic devices. Darrell Schlom, PhD, a materials science professor at Cornell University and senior author of the study, said the find beats the previous record of six eV. Reaching a bandgap of more than seven eV has been difficult because materials with wider bandgaps typically behave more like insulators. “The first reaction I heard from my scientific friends was, ‘that’s impossible,’ he said. “I must admit that, at first, the result did seem too good to be true.” Breaking the barrier Semiconductors are key for everyday electronics, including laptops, smartphones, and microwaves. Found in circuits, diodes, and transistors that keep these devices working efficiently. Their bandgap determines how much energy electrons require to move through the material. Wider bandgaps allow materials to withstand stronger electric fields. This makes them useful for high-voltage applications where energy efficiency is crucial. Still, making the bandgap wider without losing conductivity has been difficult. To tackle the challenge, the team designed thin films of aluminum gallium oxide with a technique known as suboxide molecular-beam epitaxy. It allows crystalline materials to be built up one layer at a time under carefully controlled conditions. The researchers also introduced silicon atoms into the material at a sufficiently low temperature, thus providing mobile electrons which carry electrical current. They were ultimately stunned by the final result. At room temperature, the new material conducted electricity at least 100 million times better than previously reported materials with bandgaps exceeding six eV. The team proved that it could be used in functioning electronic devices. A successful test To test the new semiconductor, the team built a diode and a field-effect transistor called AlphaFET using the material. It showed that electrical conductivity could be controlled through both silicon doping and an applied electric field. According to Huili Grace Xing, PhD, a materials science professor at the university who also worked on the project, the device achieved a change in electrical current exceeding four orders of magnitude through its metal gate. “Making a transistor allows us to simultaneously demonstrate an essential building block of electronic systems as well as several of the semiconductor’s unique properties,” Xing said. As the material was grown on sapphire, a widely available substrate that’s already produced at a larger scale, it could be easier to manufacture than other ultrawide-bandgap materials. Debdeep Jena, PhD, a materials science professor at Cornell University, said more work is needed to make the device practical, but called the new semiconductor a “game-changing platform” for the near future. Jena said that the semiconductor could improve electric vehicles, aircraft, as well as data centers. It could also have other commercial and defense applications. “Colossal bandgap semiconductors will also enable telecom relevant quantum cascade lasers and vacuum UV photonic devices that have not been possible in the past,” he concluded in a press release. The study has been published in the journal Nature.Get the latest in engineering, tech, space & science - delivered daily to your inbox.Based in Skopje, North Macedonia. Her work has appeared in Daily Mail, Mirror, Daily Star, Yahoo, NationalWorld, Newsweek, Press Gazette and others. She covers stories on batteries, wind energy, sustainable shipping and new discoveries. When she's not chasing the next big science story, she's traveling, exploring new cultures, or enjoying good food with even better wine.