Professor Ken Galloway and Research Engineer Scooter Ball of Vanderbilt University delivered this lecture for the Introduction to Radiation Effects Engineering online SCALE course.
Ion‑induced single‑event burnout (SEB) threatens the reliability of power electronics that regulate spacecraft electricity, where virtually all onboard power conversion depends on high‑voltage MOSFETs and diodes. Understanding how energetic heavy ions interact with these devices is essential for ensuring mission success in the harsh space radiation environment. The resource therefore examines the physics of power MOSFET operation and the mechanisms by which space‑borne ions can trigger catastrophic failure.
The discussion details the structure of vertical power MOSFETs, emphasizing the source, gate oxide, channel, and drift region that together determine breakdown voltage and on‑state resistance. It contrasts silicon devices (band‑gap ≈ 1.1 eV) with silicon‑carbide (SiC) devices (band‑gap ≈ 3.2 eV), highlighting SiC’s higher breakdown voltage, lower on‑resistance, superior thermal conductivity, and higher operating temperature, all of which reduce mass and power budgets for spacecraft. The presentation then describes the space radiation spectrum—total ionizing dose, X‑rays, γ‑rays, and, critically, heavy ions with linear energy transfer (LET) values that can drive a biased device into an unsafe region of its safe operating area, producing permanent metallization damage. Experimental approaches such as ion‑beam testing under controlled bias conditions and post‑irradiation failure analysis (e.g., microscopy of burned‑out regions) are outlined as methods for characterizing SEB and defining safe operating limits.
With this knowledge, learners can explain the role of power MOSFETs in spacecraft power systems and compare the trade‑offs between silicon and SiC devices. They become able to identify the specific radiation types—particularly high‑LET heavy ions—that precipitate SEB, to analyze the bias and environmental conditions that lead to burnout, and to evaluate design strategies such as material selection, voltage derating, and shielding that mitigate radiation‑induced failures in space‑flight power electronics.