Silicon Carbide-based Power Electronics for Small Fission Reactors

Fission power systems (FPS) are a candidate power source for long duration NASA surface missions to the Moon and Mars, and offer significant advantages over competing options, including longer life, operational robustness, and mission flexibility. Electronics associated with the power conversion and power management and distribution (PMAD) systems in FPS have to operate reliably under high temperature (100s of deg C), high power (1-10 kWe), and severe radiation. Silicon carbide (SiC) is a promising solution with superior electronic properties for power applications. SiC devices offer higher temperature operation, higher breakdown voltages, and higher power conversion efficiency than silicon devices. However, vulnerability to heavy-ion induced failure and uncertainty in response to nuclear radiation are challenges facing FPS applications of SiC technology. CFDRC, Vanderbilt University and Wolfspeed propose a modeling and experiment-based approach using commercial SiC technology to address this challenge. In Phase I, we will use the Geant4/MRED radiation transport code to calculate the actual neutron and gamma dose experienced by FPS electronics, derive corresponding inputs and perform TCAD modeling of SiC power diodes and MOSFETs for insight into physical mechanisms behind their response, and develop detailed radiation testing plans. We will perform x-ray testing of SiC power devices (100-1000 kRad(Si)) to obtain total dose response data. In Phase II, we will perform additional neutron, gamma, and heavy-ion tests to characterize the response of SiC devices and selected circuit versus temperature and bias. We will leverage parallel projects to analyze heavy-ion induced single-event effects in SiC diodes and MOSFETs. TCAD and mixed-mode modeling will be done to further understand radiation and temperature-dependent mechanisms and to investigate design solutions for increased radiation tolerance. Promising solutions will be prototyped, tested, and delivered to NASA.