Dosimetry and Total Dose Radiation Testing of GaAs Devices

Damage to GaAs devices from energetic electrons is shown to rise very rapidly above 600 keV. Therefore, methods of dosimetry that are more sensitive to low-energy electrons (i.e., that determine deposited energy rather than atomic displacement) could be inappropriate for GaAs. For example, a 1-MeV electron irradiation requires an order-of-magnitude lower dose (in rad) to cause the same degradation as a Co60 source in a GaAs FET. Such considerations argue against the use of rad dose to define mission radiation requirements and laboratory source calibration for GaAs devices.