Ion implantation and SiC transistor performance

SiC metal oxide semiconductor field effect transistors grown on low-doped epilayer channels and on ion-implanted channels with either "as grown" or NO annealed thermal oxides have been electrically characterized. The threshold voltage, effective electron mobility, as well as fixed charge, oxide trap, and interface trap concentrations have been separately obtained using conventional dc sweep, capacitance-voltage (C-V), fast current-voltage (I-V), and low frequency noise measurements. The results show that devices with as grown SiO2 have a much higher density of "slow" bulk oxide traps than devices after postoxidation annealing in NO. The oxide fixed charge density is unaffected by the annealing process. Devices fabricated on ion-implanted channels exhibit only a small increase in the slow bulk oxide trap density and the fixed charge. However, the density of the "fast" interface traps increases dramatically. This suggests that the damage due to the ion-implantation process is mainly interfacial. In contrast to Si devices, this ion-implantation damage is not completely repaired even after annealing.