What is an ultra-wide bandgap semiconductor material?

According to Wikipedia: Wide-bandgap semiconductors (WBG or WBGS) are semiconductor materials that permit devices to operate at much higher voltages, frequencies and temperatures than conventional semiconductor materials like silicon and gallium arsenide. They are the key component used to make green and blue LEDs and lasers, and are also used in certain radio frequency applications, notably military radars. Their inherent qualities make them suitable for a wide range of roles, and they are one of the leading contenders for next-generation devices for general semiconductor use. "Wide-bandgap" refers to higher-energy electronic band gaps, the difference in energy levels that creates the semiconductor action as electrons switch between the two levels. Silicon and other common non-wide-bandgap materials have a bandgap on the order of 1 to 1.5 electronvolt (eV). Wide-bandgap materials in contrast typically have bandgaps on the order of 2 to 4 eV.

Ultra-wide bandgap semiconductor (UWBGS) materials are a subset of WBGS and are defined as those WBGS materials which have a bandgap above that of GaN, which is 3.4 eV. This includes materials such as diamond, gallium oxide (Ga2O3), AlGaN, and AlN. UWBGS materials have the potential to support the realization of devices with even higher levels of performance than that of devices based on Si, GaAs, SiC, or GaN.