Compensation-circuit to improve radiation-hardness in GaAsdigital-circuits, based on X-ray studies

摘要

Earlier results have shown that GaAs devices do not exhibitnappreciable degradation up to a radiation dose of nearly 108nrad (GaAs). The results of this work suggest that GaAs devices andncircuits are sensitive to radiation exposure at dose levels belown108 rad(GaAs). Degradation was observed in E-MESFET andnD-MESFET parameters and in circuit performance for devices which werendesigned and fabricated in a 1.2 Μm GaAs process, when exposed tonvarying doses of 1.49 keV X-rays in the range 40-65 Mrad (GaAs). Thendegradation is attributed to the change in the properties of the MESFETnchannel region, caused by the transport of the atomic hydrogen from thenpassivation layer to the channel. A compensation circuit, based on thenobserved behavior of radiation effects on GaAs devices, has beenndesigned to improve the radiation insensitivity of GaAs (E/D) basedncircuits under SPICE (Simulation Program with IC Emphasis) simulatednconditions. Its usefulness is demonstrated through a DCFL inverterncircuit up to nearly 108 rad (GaAs) dose level. The resultsnof this work can be used in the design of complex-functionnradiation-insensitive DCFL based circuits