Self-Heating Effects and Thermal Mitigation Strategies in Ferroelectric ScAlN/GaN HEMTs

We investigate self-heating effects (SHE) and thermal mitigation strategies in ferroelectric ScAlN/GaN high-electron-mobility transistors (HEMTs). Molecular beam epitaxy (MBE)-grown devices demonstrate a large memory window (MW) of ~3.8 V, on/off current ratio (I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub>/I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub>) >10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup>, and sub-Boltzmann subthreshold swing (SS) ~20 mV/dec, enabled by ScAlN polarization control of the two-dimensional electron gas (2DEG). Under high drain bias, SHE degrades memory and subthreshold characteristics. The thermal origin of degradation is confirmed by external heating and transconductance analysis. Multi-frequency conductance measurements reveal charge trapping and detrapping, which may be accelerated by SHE. Heat sink integration effectively reduces temperature rise, as verified by scanning thermal microscopy. These results underscore the importance of thermal management for reliable ferroelectric HEMT operation in high-power and extreme-environment applications.