Fast Neutron Effects on GaAsP Schottky Barrier Diodes and Hall Effect Devices

GaAsP Schottky barrier diodes and Hall effect devices were exposed to fast neutron radiation at room temperature at fluences ranging from 1013 neutrons cm-2 (E > 10 keV) to 8.9 × 1016 neutrons cm-2 (E > 10 keV). The carrier removal rate for the n-type material with a nominal doping of 5 × 1015 cm-3 and irradiated at a fluence of 9.7 × 1014 neutrons cm-2 (E > 10 keV) was determined from the capacitance-voltage characteristics of the diodes and was found to range between 5 and 6 cm-1. The change in conductivity of the GaAsP with neutron radiation measured on the Hall effect devices agrees very well with the diode measurements, while the change in effective carrier concentration appears to be slightly greater in the diodes than in the Hall devices. The Hall effect device measurements showed that the GaAsP material tends to become intrinsic after irradiation at high neutron fluence levels. The decrease in minority carrier lifetime after neutron irradiation was observed from the transient photocurrent response of the neutron-irradiated diodes generated by an ionizing X-ray pulse. Isochronal annealing of the neutron-irradiated diodes showed approximately a 40 percent recovery in carrier concentration over a wide temperature range starting at 225°C and continuing up to the maximum annealing temperature of 580°C.