Characterization and modeling of high voltage SiC PN diode

Silicon carbide is seen as a potent material for high power, high temperature and harsh environment applications because of its large band-gap, the consequently greater breakdown electric field, higher thermal conductivity and electron saturation velocity. However the commercial use of SIC devices is prohibited by the immature process technology and wafer quality deficiencies. While the most degrading micropipe defects have been significantly reduced in number, other defect types like screw dislocations continue to contaminate SiC devices in large quantities. This paper models the presence of embedded screw dislocation type defects for SiC PN junction diodes. The defects are presented as parallel diodes to the ideal ones with areas correspondingly reduced. Since the defects affect the I-V characteristics severely, these are studied in detail. Defect diodes are shown to turn on earlier to the ideal ones depending upon their built-in voltage, thus giving an anomalous bump in the initial part of forward I-V curves. The extracted diode structure is simulated in a 2-D finite element simulator and the static characteristics and forward I-V curves matched. Reverse recovery characteristics are also studied and found to vary very slightly with forward current