In microelectronic devices, the bandgap is a major factor determining the electrical conductivity of the underlying materials. Substances with large bandgaps are generally insulators that do not conduct electricity well, and those with smaller bandgaps are semiconductors. A more recent class of semiconductors with ultrawide bandgaps (UWB) are capable of operating at much higher temperatures and powers than conventional small-bandgap silicon-based chips made with mature bandgap materials like silicon carbide (SiC) and gallium nitride (GaN).