FAILURE MECHANISMS IN ALGAAS/GAAS HEMTS

Failure mechanisms in AlGaAs/GaAs high electron mobility transistors (HEMTs) life tested under high temperature storage, high temperature with d.c. bias, and high temperature with d.c. bias under r.f. drive have been determined to differ significantly. Monte Carlo modeling has been used to explain the experimental data, which shows evidence of gate sinking, ohmic contact degradation, and trapped charge formation near the two-dimensional gas (2DEG). Of particular interest is the evidence of damage from hot carriers under the stress conditions of high temperature with d.c. bias under r.f. drive, which most closely simulates actual use conditions.