Isolation degradation of InAlAs/InGaAs/InP HEMTs due to bias stressdepending on passivation films formed by PCVD

摘要

We have observed the degradation of pinch-off characteristics ofInAlAs/InGaAs high electron mobility transistors (HEMTs) with SiNpassivation film after the bias stress test, which has been resultedfrom an increase of leakage current on InP surface. On the other hand,the device passivated by SiO₂ film does not show anydegradation. The stability of the isolation characteristic for InP isstrongly affected by the surface passivation film formed byplasma-enhanced chemical vapor deposition (PCVD). In order to improvethe device reliability, SiO₂ is more suitable than SiN for astable passivation to InP surface