Linear energy transfer dependence of single event gate rupture in SiC MOS capacitors

Metal-oxide-semiconductor (MOS) capacitors were fabricated on n-type 4H silicon carbide (SiC) epitaxial layers grown on n-type 4H-SiC substrates, and the currents through the gate oxide of the MOS capacitors were measured under accumulation bias conditions during heavy-ion irradiation. Evaluation of the linear energy transfer (LET) dependence of the critical electric field (Ecr) at which dielectric breakdown occurred in these capacitors revealed that the reciprocal of Ecr (1/Ecr) increased linearly with increasing LET. The slope of LET dependence of 1/Ecr for SiC is lower than that for Si, suggesting that SiC MOS devices are less susceptible to single-event gate rupture (SEGR) than Si MOS devices. The limitation of previously proposed SEGR models based on SiO2 on Si is discussed, as is the importance of the physical parameters of the oxide and semiconductor materials (bandgap, carrier lifetime and mobility, etc.).