High energy neutron irradiation effects in GaAs modulation-doped field effect transistors (MODFETs)

The effects of high energy neutrons on MODFETs have been studied for fluences approaching 1 x 10/sup 15/ cm/sup -2/. Neutron induced threshold voltage shifts are described by application of a finite temperature strong inversion, depletion layer, charge control model. The model indicates that the neutron induced threshold voltage shift is a consequence of electron trapping in the GaAs layer near the AlGaAs/GaAs interface. The authors analysis shows that neutron degradation in these AlGaAs/GaAs heterostructures is dominated by the change in the depletion layer charge and the shift in the Fermi level with neutron fluence. These dominant mechanisms are shown to depend on GaAs material parameters, only. The AlGaAs layer carrier removal accounts for <3% of the total threshold voltage shift