Reliability and degradation mechanism of AlGaAs/InGaAs and InAlAs/InGaAs HEMTs

The long-term stability of AlGaAs/GaAs and InAlAs/InGaAs high electron mobility transistors (HEMTs), tested under high drain voltage and/or high temperature operation is reported. HEMTs with high In content in the active channel, alternatively fabricated on InP substrates and on GaAs substrates covered by a metamorphic buffer (MHEMT), are compared. Despite the high dislocation density in the buffer layer MHEMTs and InP based HEMTs exhibit comparable reliability. AlGaAs/GaAs HEMTs are more reliable than their InAlAs/InGaAs counterparts, especially when operated at high drain voltage. Failure mechanisms are thermally activated gate sinking, Ohmic contact degradation and hot electron induced degradation.