This SPIE paper by Handel and Morkoç examines piezoelectric quantum 1/f noise in AlGaN HFETs and reliability. The research investigates how piezoelectric-induced quantum 1/f noise correlates with reliability and degradation in aluminum gallium nitride high electron mobility transistors, showing that low-frequency noise measurements can serve as early indicators of defect formation, trap generation, and impending failure, providing non-destructive diagnostic tools for assessing device quality and predicting long-term reliability in GaN-based power amplifiers and switches.