Analysis of GaN HEMT Failure Mechanisms During DC and Large-Signal RF Operation

An analysis of the reliability of GaN high-electron-mobility transistors during dc and RF stress tests is presented. Competing degradation mechanisms have been observed during RF operation, demonstrating the dependence of device reliability on device RF driving conditions. DC tests revealed only one degradation pattern related to defect formation at the high-electric-field region of the gate contact. RF signals, however, allow for other physical phenomena to take place before the said defect formation. Electron injection on the gate-drain region decreases the electric field value, thus counteracting the electric-field-induced defect formation at the gate edge.