This SPIE-PW paper by Handel, Sherif, Kayis, Leach, Zhu, and Morkoç demonstrates that 1/f noise serves as a window to HFET stability. The research shows that low-frequency noise measurements provide diagnostic information about defect states, trap dynamics, and degradation processes in heterostructure field-effect transistors, establishing correlations between noise parameters and device reliability, enabling predictive testing and quality control for ensuring long-term stable operation of GaN and other compound semiconductor transistors.