RELIABILITY OF LOW-NOISE HEMTS UNDER GAMMA-RAY IRRADIATION

Gamma(gamma)-ray irradiation effects have been investigated on three t ypes of low-noise HEMTs, AlGaAs/GaAs conventional HEMT (conv. HEMT), A lGaAs/InGaAs pseudomorphic HEMT (P-HEMT) and InAlAs/InGaAs/InP HEMT (I nP-based HEMT). The dose of irradiated gamma-rays ranges from 1 x 10(5 ) to 1 x 10(8) rad. DC and RF characteristics of each type of HEMT are measured before and after irradiation and the parameter changes are i nvestigated. For conv. HEMT and P-HEMT, no degradation of DC parameter is observed up to 10(8) rad, while noise figure (NF) at 12 GHz remain s constant up to 10(7) rad and degrades by 0.1 dB at 10(8) rad. The In P-based HEMT shows I(DSS) and g(m) increase by about 10% at a dose of 10(8) rad and its NF at 18 GHz lowers gradually with the radiation dos e. It has been found that the radiation hardness is greater than 10(7) rad for all types of HEMTs and over a hundred years of life can be ex pected against gamma-ray irradiation in the space environment.