Characterization and modeling of the mobility, threshold voltage, and subthreshold swing in p-GaN gate HEMTs at cryogenic temperatures.

This article focuses on the electrical characterization and modeling of p-GaN gate high-electron-mobility transistors (HEMTs) operating under cryogenic temperatures from 300 K down to 10 K. The study demonstrates that these devices achieve a low subthreshold swing (SS) below 60 mV/dec (33.2 mV/dec at 10 K), a high on/off current ratio (~3.5 × 10¹⁰ at 10 K), and a high maximum drain current (~358 mA/mm at 10 K). It further models key parameters such as mobility, threshold voltage shifts, and SS behavior at cryogenic temperatures, attributing SS saturation to band tail effects in the AlGaN barrier. The findings suggest that p-GaN gate HEMTs, due to their resistance to carrier freeze-out and favorable electrical properties, are promising candidates for cryogenic power electronics applications including quantum computing and spacecraft systems.