Researchers at the University of Illinois have developed a three-dimensional high electron mobility transistor (HEMT) architecture that utilizes ultra-wide bandgap (UWBG) materials. These structures and devices can be used for high-power, high-frequency applications, where they can confer an order of magnitude higher performance than wide bandgap (WBG) devices, including simultaneously achieving 10x higher power density while operating at frequencies as high as 120 GHz.