| We studied passivation effects of various dielectric films for GaAs MESFETs, AlGaAs/GaAs pseudo-morphic HEMTs, AlGaN/GaN HEMTs and AlGaAs/GaAs HBTs in terms of dc current-voltage characteristics, small signal responses, pulse and power measurement.;To prolong device lifetimes, depositions of passivation films play an important role in stabilizing device performance under biasing conditions. We used a plasma enhanced chemical vapor deposition (PECVD) system to investigate plasma-induced damage effects and passivation effects with different discharges such as N2, H2 or D2. Three damage mechanisms are found after plasma exposures; creation of deep traps, preferential loss of As from the surface and passivation of acceptors or donors.;Radiation hard investigations were conducted with exposure of Cobalt 60 and gamma sources to a variety of compound semiconductors devices. The irradiation doses corresponding to 10--100 years in low earth orbit could cause 30--50% degradation in device performance.;Hydrogen-free, MBE-grown oxides use to passivate surface traps and suppress the current collapse phenomena of AlGaN/GaN HEMTs. We examined three different passivation films (SiNX, MgO and Sc2O3) for their effectiveness in mitigating surface-state-induced current collapse in AlGaN/GaN HEMTs. Conventional PECVD SiNX could recover 70--80% current level. Both the SC2O3 and MgO passivated device produced essentially complete recovery of the current in GaN-cap HEMT structures and ∼80 to 90% recovery in AlGaN-cap structures. In addition, the Sc2O3 had superior long-term stability, with no change in HEMT behavior over 5 months of aging. |
