The role of defects on forward current in 4H-SiC p-i-n diodes

We investigated the impact of defect states on the measured forward current-voltage (I-V) curves of ion-implanted planar 4H-SiC p-i-n diodes of a different anode dimension by means of a fine-tuned numerical model. Cross sections and activation energies of defects related to the carbon vacancy (EH and Z) and Titanium (Ti) impurity used in our model were experimentally identified in the diodes of the same batch. We analyzed the effect of each individual defect on the I-V curves and estimated the unknown hole capture cross sections by ensuring the optimal match between simulated and measured currents. Small discrepancies between measured and simulated forward current-voltage curves of diodes of equal shape but a different perimeter-to-area ratio has been accounted for by considering, in the simulations, the presence of a fixed positive charge at the diode surface. By using this procedure, diodes of every dimension have been simulated without the use of adjustment parameters. These results are valuable in understanding the role of defects in the I-V curves of the ion-implanted SiC diode.