Edge termination design for 1.7 kV silicon carbide p- n diodes

In this work, in order to obtain breakdown voltage values of the 4H-SiC p-i-n diodes above 1.7kV, three designs have been examined: single-zone junction termination extention (JTE), double-zone JTE and a structure with concentric rings outside each of the areas of the double-zone JTE (space-modulated JTE). The influence of geometry and the level of p-type doping in the JTE area as well as the charge at the interface between the p-type JTE area and the passivation layer on the diode breakdown voltage was studied. The effect of statistical dispersion of drift layer parameters (thickness, doping level) on diodes breakdown voltage with various JTE structures was investigated as well. The obtained results showed that the breakdown volatge values for a diode with single zone JTE are very sensitive both to the dose of JTE area and charge accumulated at the JTE/dielectric interface. The use of a double zone or space-modulated JTE structures allows for obtaining breakdown voltage above 1.7 kV for a much wider range of doping parameters and with better tolerance to positive charge at the JTE/dielectric interface, as well as better tolerance to statistical dispersion of active layer parameters compared to a single zone JTE structure.