Gallium nitride (GaN)-based high electron mobility transistors (HEMTs) are a type of field-effect transistors (FETs) designed to operate at very high frequencies with low noise. As such, they have been widely applied in high-power and high-frequency applications, like high-speed wireless communications, power switching devices, and power amplifiers.

HEMTs utilize a heterojunction, which is a junction between two different semiconductor materials, typically GaN and aluminum GaN (AlGaN). This junction creates a narrow region called the two-dimensional electron gas (2DEG), where electrons have very high mobility, resulting in excellent high-frequency performance.

Scandium aluminum nitride (ScAlN) has attracted significant attention as a novel barrier material that can further enhance the performance of GaN HEMTs. It exhibits large polarization, which increases electron densities in the 2DEG. Additionally, its ferroelectric nature makes it suitable for use as a ferroelectric gate material in ferroelectric HEMTs.