Transient Analysis of an Extended Drift Region in a 6H-SiC Diode Formed by a Single Alpha Particle Strike and Its Contribution to the Increased Charge Collection

Charge collection of a 6H-SiC p⁺ n diode has been studied. The collected charges of the diode are measured using a single alpha particle strike at various reverse bias voltages, then analyzed using both the low-injection charge collection model and the DESSIS device simulator. It is found that the total collected charges at lower bias voltages cannot be well understood based on the low-injection model. In distinct contrast, the device simulator successfully predicts the total collected charges at all voltages including the lower ones. The transient analysis of carrier and electric field distributions after the strike shows insignificant collapse of the original depletion region and time-dependent extension of the electric field beyond the original depletion region. A new physics is proposed to explain slower rearrangement of carriers, compared to Si devices, and formation of an extended drift region in the 6H-SiC diode based on the results of the transient analysis.