| Popis: |
The electrical and switching characteristics of high power semiconductor switches subjected to high levels of neutron fluences and gamma doses must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect switch performance are briefly discussed. The effects of post‐irradiation thermal anneals at 300 K and up to 425 K for NPN Bipolar Junction Transistors (BJTs), N‐channel Metal‐Oxide‐Semiconductor Field Effect Transistors (MOSFETs), and N‐channel Static Induction Transistors (SITs) are discussed in terms of recovery of degraded electrical and switching parameters caused by either neutron or gamma irradiation. The important experimental results from these annealing tests show that BJTs have very good recovery to leakage current degradation but poor recovery to current gain degradation; MOSFETs show some recovery in gate‐source threshold voltage degradation but no significant recovery in drain‐source on‐resistance degradation; and likewise, SITs show no significant recovery in drain‐source on‐resistance degradation. |
