Ionizing Radiation Effects in InP MISFETs

Long-term transient responses were observed in enhancement mode InP MISFETs following single 50 ns pulses of 40 MeV electrons at levels between 0.45-10.5 Krads per pulse. The measured change in drain current, IDS´ depended on bias conditions and was between 10-48% for different devices under high current operating conditions. Recovery times were 50-200 ¿s and 3 ms depending on the device, and all devices exhibited long-term drift in IDS of longer than 5 min. When these devices were exposed to gamma radiation while under high current conditions, large threshold voltage, Vth, shifts were observed at low doses. These shifts were time-dependent, amounting to a minimum of -0.6V immediately following a total dose exposure of 5 Krads. The devices were unstable following irradiation and Vth exhibited a drift component for periods longer than 30 min.