Neutron Radiation Effects in Gold and Aluminum GaAs Schottky Diodes

The electrical characteristics of guarded Au- and Al-n GaAs Schottky diodes with free carrier concentration in the range of 3 x 1015 to 8 x 1016 cm -3 have been determined after neutron irradiation. Low neutron fluences producing carrier removal rates less than 20% cause a slight change in the C-V and the forward I-V characteristics but increase significantly the reverse current. Assuming Levine's model for a Schottky barrier, the slight changes in the I-V characteristics at forward bias and small reverse bias voltage have been attributed to a change in the distribution of interface states at the metal-semiconductor interface. The excess, non-thermionic reverse current observed after low fluence neutron irradiation is not due to surface leakage or classical generation-recombination but appears to be due to a high field process. Consideration of several high field effect mechanisms indicates that field emission from a deep level is the likely cause.