About the Nature of Recombination Current in 4H-SiC pn Structures

The forward current was investigated in 4H-SiC p+n structures grown by sublimation epitaxy. The doping level, Nd-Na, of the n-layer was about (3-4)x1016 cm-3 and the diode area was in the range from 1x10-5 to 2x10-4 cm2. The observed current can be considered as current due to bulk recombination in the space charge region of the pn junction via deep level center or due to surface recombination. The criterion which was performed in this study to differentiate such currents was the investigation of recombination current versus perimeter/area ratio dependence. It was found that no pronounced difference in the recombination current parameters for diodes with different perimeter/area ratio was observed, i.e. current due to surface recombination was not observed for the 4H-SiC pn structures investigated.

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