A semiconductor device comprises a first layer (1) of a wide band gap semiconductor material doped according to a first conductivity type and a second layer (3) on top thereof designed to form a junction blocking current in the reverse biased state of the device at the interface to said first layer. The device comprises extension means for extending a termination of the junction laterally with respect to the lateral border (6) of the second layer. This extension means comprises a plurality of rings (16-21) in juxtaposition laterally surrounding said junction (15) and being arranged as seen in the lateral direction away from said junction alternatively a ring (16-18) of a semiconductor material of a second conductivity type opposite to that of said first layer and a ring (19-21) of a semi-insulating material.