We have evaluated radiation-induced charge trapping and low-frequency noise in passivated black phosphorus (BP) MOSFETs with HfO2 gate dielectrics. Thinning the gate dielectric reduces total ionizing dose-induced threshold voltage shifts. The defect-energy distribution estimated from low-frequency noise measurements performed as a function of temperature decreases with increasing energy in as-processed devices. Local maxima in noise magnitude are observed in irradiated devices at activation energies of ∼0.2 and ∼0.5 eV. Larger defect-related peaks in noise magnitude in the range of 0.35-0.5 eV are observed after biased post-irradiation annealing, and/or vacuum storage of the devices after irradiation and annealing. Density functional theory calculations strongly support significant roles for O vacancies in HfO2 and H+ transport and reactions near the BP/HfO2 interface in the observed radiation response and low-frequency noise.
Bibliographical noteFunding Information:
Manuscript received January 16, 2018; revised April 12, 2018; accepted April 13, 2018. Date of publication April 19, 2018; date of current version June 13, 2018. This work was supported in part by the Defense Threat Reduction Agency Basic Research under Award HDTRA1-14-1-0042 and in part by the National Science Foundation under Grant DMR-1508433.
© 2018 IEEE.
- Black phosphorus (BP)
- low-frequency noise
- moisture effects
- switched-bias annealing
- total ionizing dose (TID)