Abstract: This document details the results of a cosmic ray radiation test performed on two planar SiC power MOSFET technologies belonging to the 650V and 1200V voltage classes. The testing followed JEDEC standard JEP151A, using a 200 MeV proton beam to simulate the effects of cosmic ray-induced single event burnout (SEB). The testing involved comprehensive pre?characterization, real-time monitoring during irradiation, and post-exposure analysis. Key parameters like Failure In Time (FIT) were computed across different operating voltages and the results are compared against data from various SiC Mosfets available in public literature. 9. Test Results The test results revealed key insights into the radiation tolerance of both the 1200V and 650V SiC MOSFETs. For each tested voltage level, the devices were monitored for failure signatures, and their corresponding fluence values were recorded. Using this information, the Failure In Time (FIT) metric was computed. FIT values were then plotted against applied high voltage (VDS) to investigate trends and voltage sensitivity. These results are plotted in Figure 8, assuming a neutron flux value n= 1/cm2/h. Error bars represent 2σ confidence intervals based on sample variation and flux uncertainty. As expected, the FIT rates increase with applied voltage for both technologies. The 1200V SiC MOSFET has a higher FIT rate compared to its 650V counterpart, because the former has a higher chip area compared to the latter. It is important to note the exponential scaling on the y-axis, which means that FIT rate increases near-exponentially with increase in applied voltage. Therefore, the applied dc-link voltage in the application has to be within suitable limits to limit the FIT rate. As the FIT rate is dependent on the chip size, it is desirable to normalize the FIT rates according to the active area of the chip for comparability. They have also been normalized according to their actual breakdown voltage (obtained from pre-characterization). Furthermore, the results have been normalized to n= 13/cm2/h, which is the reference neutron flux for New York City at sea level as per JEDEC JEP89 [4]. This is considered, as it makes it comparable to results from state-of-the-art devices available in literature, as will be explained in the later part of this paper. The resulting FIT rates are plotted in Figure 9. It can now be seen that both technologies, though having different breakdown voltages arising from different doping and thickness of the drift layer, behave similarly. This confirms that the SEB effects are mainly dictated by how close the working voltage (Vdc) is with respect to the designed breakdown voltage. This also implies that the drift layer has to be appropriately dimensioned for a given Vdc, to meet certain FIT targets. In order to compare how these devices fare compared to other SiC Mosfets available in the market, the measured results were compared against data available from literature. FIT rates documented for several competitors in [5] were replotted as-they-are and compared against the above mentioned results in . It can be confirmed that the measured FIT rates for both the tested devices are in the same ball park as the FIT rates measured on devices from other suppliers. 10. Summary and Conclusion This study evaluated the susceptibility of two types of Silicon Carbide (SiC) planar MOSFETs—1200V SiC MOSFET and 650V SiC MOSFET—to radiation-induced destructive effects. The tests were conducted using a 200 MeV proton beam, following JEDEC JEP151A. standard procedures for simulating terrestrial neutron effects. Each device type was tested across a range of high voltage conditions. All devices were monitored in real-time using a custom data acquisition system. Failures were detected by tracking sudden drops in VDS accompanied by spikes in IDS. These failure points were used to compute FIT (Failure In Time) values normalized to a reference neutron flux of 1 n/cm²/h. The key findings are as follows: • Post-irradiation IV curves confirmed irreversible degradation and increased leakage currents. • FIT values showed an exponential dependency on the applied drain-source voltage (VDS), as expected. • When plotted as function of the ratio of the applied voltage to the designed breakdown voltage, FIT rates for both technologies match well, as expected from literature. • The FIT rates for both the tested devices were compared against FIT rates known from literature for devices from other suppliers. The FIT rates for the tested devices lie in the same ball park as the data from other suppliers, confirming a comparable level of sensitivity to cosmic radiation. The study demonstrates that SiC MOSFETs, while robust under many conditions, remain vulnerable to SEB when exposed to high-energy protons at elevated voltages. Optimal selection of devices, especially regarding the designed breakdown voltage, to meet a given application is crucial to ensure reliable operation.