Effect of overlap region for schottky metal and field oxide on the electrical characteristics of 6500 V/50A 4H-SiC JBS diodes

•The reverse breakdown voltage of 6500 V/50A 4H-SiC JBS diodes was studied.•The reverse voltage is up to 7000 V at the reverse leakage current of 10 μA.•The electric field of the simulative diodes reduced by about 30%-50%.•The experimental results are in good consistent with the simulation results. The effect of overlap region for schottky metal and field oxide (ORSMFO) of field limiting rings termination on the reverse breakdown voltage of 6500 V/50A 4H-SiC JBS diodes was studied. Two comparative diodes were designed and fabricated. The reverse breakdown voltage of diodes with 20 μm ORSMFO improved significantly, which was up to 7000 V at the reverse leakage current of 10 μA and yield was up to 73 %. The structure simulation implied that the difference of the ORSMFO influenced the electric field strongly. Compared with the simulative terminal structure with 3 μm and 0 μm ORSMFO, the electric field intensity of the simulative terminal structure with 20 μm ORSMFO reduced by about 30 %-50 % near the main junction and the first three field rings.