Electrical Reliability of RF Power GaAs PHEMTs

GaAs PHEMTs are broadly used in RF power applications for wireless systems. A major concern with these devices is their gradual degradation as a result of prolonged biasing at high voltages. Previous research has identified the drain side of the device as the region that sustains most of the damage [1], but other mechanisms involving charge modulation under the gate [2] have also been reported. Impact ionization and hot-carrier effects have been closely correlated with electrical degradation [1]-[4], but the details of the physics behind the degradation are not known. In this research, we carry out a systematic investigation of the degradation of RF power PHEMTs under prolonged electrical stress. By examining devices with different geometries as well as TLM test structures, our research isolates degradation mechanisms that separately affect each of the three main regions of the device: source, gate and drain.