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 h eterojunction FETs and of amplifiers based on these devices before and after irradiation with neutrons for a total fluence of 1.1 x 10(15) n /cm(2). Measurements were made on the threshold voltage, the transcond uctance, the saturation drain current and the gate leakage current of the discrete transistors. For the preamplifiers, DC and AC characteris tics as well as their input referred noise were measured. All devices remained fully functional after irradiation, with no anomalous behavio ur. The overall change in transistor parameters after irradiation was typically 10%. The DC and AC characteristics of the amplifiers were fo und to remain stable after neutron irradiation. There is a slight incr ease 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 wit h 330 mu m input FET.