Degradation mechanisms of GaAs PHEMTs under operation in high humidity conditions

We have comprehensively investigated the degradation mechanism of AlGaAs/InGaAs pseudomorphic highelectron- mobility transistors (PHEMTs) under operation in high humidity conditions. The degraded samples under high humidity condition with bias show a decrease in maximum drain current (I_max).The decrease of I_max is accelerated with increasing drain voltage, temperature and humidity. The PHEMT degradation is caused by corrosion reaction at the semiconductor surface at drain side. The rate of corrosion degradation is increased by RH³. Higher V_gd decreases the actual activation energy for corrosion. The degradation depends on surface treatment prior to deposition of a SiN_x passivation film.The reduction of As-oxide at SiN_x/semiconductor interface might suppress the corrosion reaction.