Comparative study on total ionizing dose effects of silicon carbide-based and silicon-based power MOSFETs

Background Silicon carbide (SiC) power MOSFETs offer significant advantages, including low conduction losses, high switching speeds, and superior high-temperature tolerance, making them highly suitable for space applications. Nevertheless, SiC MOSFETs deployed in space face reliability risks induced by total ionizing dose (TID) effects. Compared to conventional Si MOSFETs, whether SiC MOSFETs exhibit superior TID hardness remains an open question.

Purpose This paper presents a comparative study on the TID tolerance of six commercial SiC MOSFETs based on ⁶⁰Co γ-ray irradiation tests. Furthermore, their performance is benchmarked against two Si power MOSFETs. The experimental data provide critical insights for the selection of power MOSFETs intended for space applications.

Methods Since the threshold voltage is the most sensitive parameter to TID effects, this paper preliminarily evaluates the TID tolerance of different types of power MOSFETs based on a comparison of threshold voltage shifts.

Results The experimental results show that the 900 V-rated SiC MOSFET exhibits a threshold voltage shift of −0.325 V after irradiation with a total dose of 500 krad(Si) under unbiased conditions. Whereas under the same bias and dose conditions, the 900 V-rated Si MOSFET shows a threshold voltage shift as large as −5.662 V. For different kinds of 1200 V planar SiC MOSFETs, the average threshold voltage shifts range between −0.428 V and −0.297 V after 500 krad(Si) irradiation. While the 1200 V trench SiC MOSFET exhibits an average threshold voltage shift of −2.019 V after the same dose irradiation.

Conclusions The TID irradiation tolerance of SiC power MOSFETs is significantly superior to that of Si MOSFETs, which may be attributed to the thinner gate oxide thickness of SiC devices. Comparing the two structures of planar and trench SiC MOSFETs, trench devices show a more pronounced threshold voltage shift after irradiation. This may be related to the special morphology and stress distribution of the trench gate oxide. The results indicate that, under the same irradiation conditions, planar SiC MOSFETs exhibit superior TID tolerance compared to trench SiC MOSFETs, while trench SiC MOSFETs outperform planar Si MOSFETs.