`Classical' current-voltage characteristics of 4H-SiC p⁺-n junction diodes

Forward current-voltage characteristics of 4H-SiC p⁺-n diodes with 5.5 kV voltage-blocking capacity have been studied in the temperature range 297-640 K. `Classical' characteristics, described as a sum of the recombination current in the space charge region and the diffusion current in the base, have been observed for the first time at low current densities over the whole temperature range. Using data on the saturation diffusion current, the hole lifetime in the base is estimated to be about 10^-9 s. This value is three orders of magnitude shorter than the hole lifetime measured in the same structures at high injection level. The possible reasons for such a discrepancy are discussed.