Low-Frequency Noise Due to Iron Impurity Centers in GaN-Based HEMTs

Commercial Schottky-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) exhibit a large peak in low-frequency (LF) noise magnitude at
$\sim $
325 K. An activation energy of 0.56 ± 0.05 eV is determined for the responsible generation–recombination (G–R) center via Arrhenius analysis. Comparisons with first-principles calculations and complementary experimental studies show that this G–R center is due to substitutional iron impurities, FeGa. Independent determination of the activation energy for this prominent noise peak enables recalibration of the Dutta–Horn model of LF noise for GaN-based HEMTs and a downward revision by
$\sim $
20% of past LF-noise estimates of effective defect energies. The resulting LF-noise-derived defect-energy distributions are consistent with deep-level-transient spectroscopy (DLTS) measurements on GaN-based diodes before and after 1.8-MeV proton irradiation. The activation of FeGa-related centers via defect dehydrogenation during high-voltage stress is demonstrated via LF noise measurements on AlGaN/GaN-on-SiC HEMTs.