Characteristics of GaAs complementary heterojunction FETs (C-HFETs) and C-HFET based amplifiers exposed to high neutron fluences

This paper discusses the electrical properties of complementary GaAs heterojunction FETs and of amplifiers based on these devices before and after irradiation with neutrons for a total fluence of 1.1 × 1015 n/cm2. Measurements were made on the threshold voltage, the transconductance, the saturation drain current and the gate leakage current of the discrete transistors. For the preamplifiers, DC and AC characteristics as well as their input referred noise were measured. vices remained fully functional after irradiation, with no anomalous behaviour. The overall change in transistor parameters after irradiation was typically 10%. The DC and AC characteristics of the amplifiers were found to remain stable after neutron irradiation. There is a slight increase in 1/f noise: For a total input capacitance of 1 pF and a shaping time of 50 ns an increase in the total ENC from 150 electrons before to 180 electrons after irradiation was measured for a preamplifier with 330 μm input FET.