Total ionizing dose effects on HfO₂-passivated black phosphorus transistors

Electrical stress and 10-keV x-ray irradiation and annealing responses are evaluated for HfO₂-passivated black phosphorous (BP) MOSFETs with HfO₂ gate dielectrics. Device characteristics are stable during constant gate-voltage stress up to at least ±1 V. Significant negative threshold shifts, mobility degradation, and increases in subthreshold swing occur during both positive and negative bias irradiation. Hole trapping in the HfO₂ gate dielectric dominates the TID response in these passivated BP MOSFETs. Reversibility of electrical parameters and magnitude of low frequency noise is observed during switched-bias annealing after irradiation. The voltage dependence of the low-frequency noise suggests that the trap distribution of the defects contributing to the noise becomes more uniform in energy after the devices are irradiated and annealed.