Gamma Irradiation Effects on 4H-SiC MOS Capacitors and MOSFETs

The effects of gamma radiation on field effect mobility and threshold voltage have been studied for lateral n-channel 4H-SiC MOSFETs passivated with nitric oxide. MOS capacitors (n and p) and n-channel lateral MOSFETs were irradiated unbiased (floating contacts) for a total gamma dose of 6.8Mrad (Si). The MOS capacitors were used to study the radiation-induced interface traps and fixed oxide charge that affect the performance of the MOSFETs. Radiationinduced interface traps were observed near the SiC valence band edge and just above mid-gap, and field effect channel mobility was reduced by 18-20% following irradiation. Even so, 4HMOSFETs appear to be more radiation tolerant than Si devices.