AN ALGAAS/INGAAS PSEUDOMORPHIC HIGH-ELECTRON-MOBILITY TRANSISTOR WITH IMPROVED BREAKDOWN VOLTAGE FOR X-BAND AND KU-BAND POWER APPLICATIONS

This work determined that RF drain current degradation is responsible for the poor power performance of wide-recessed PHEMT. A model based on surface states was proposed to explain this phenomenon, which then led to the use of charge-screen layers and a double-recessed gate process to suppress surface effects. Combined, these two modifications increased the device's gate-drain reverse breakdown voltage without causing a degradation in the transistor's RF drain current. This allowed the simultaneous achievement of high power-added efficiency and high power density which established a new performance record for power PHEMTs at X- and Ku-bands. Delay time analyses of single- and double-recessed PHEMTs revealed that the benefit of a larger breakdown voltage in the latter device design came at the cost of a larger drain delay time. Drain delay accounted for 45% of the total delay when the 0.35 mum. double-recessed PHEMT was biased at V(ds), = 6V.