CARRIER REMOVAL AND CHANGES IN ELECTRICAL-PROPERTIES OF NEUTRON-IRRADIATED GAAS

The changes in electrical properties of n-GaAs as a result of irradiations with fast neutrons have been studied. Epitaxial layers doped with Si at concentrations in the range 1.35 x 10(15) to 1.599 x 10(16) cm-3 were irradiated with reactor neutron fluences up to 1.31 x 10(15) cm-2. When the changes in carrier concentration, Hall mobility, and resistivity were more than 25% of their initial values, nonlinear dependence on neutron fluence was apparent. New theory is proposed which explains the changes in electrical properties in terms of rates of trapping and release of charges. A theoretical relationship is derived for the change in carrier concentration as a function of neutron fluence and doping level. A linear relationship between neutron fluence and Fermi level shift was found to be consistent with the observed changes in carrier concentration.