Gate turn-off diodes and arrangements including such diodes

A gate turn-off diode for power switching applications which comprises a semiconductor body having first and second opposite major surfaces, and comprising an n-type cathode region, a p-type anode region, a base region of a first conductivity type and a higher resistivity than that of said cathode and anode regions, a main current path which extends thorugh said base region between the cathode and anode regions, the base region having a conductivity-type-determining dopant concentration of at most about 5.times.10.sup.14 atoms per c.c. and forming a first p-n junction with one of the cathode and anode regions, a gate region which is of a second conductivity type opposite to that of the base region and forms with the base region a second p-n junction adjacent the main current path, and a gate electrode connected to the gate region for biasing the second p-n junction to permit interruption of said current path by forming a depletion layer, which extends from the biased second p-n junction toward said cathode and anode regions, said cathode and anode regions adjoining said first major surface and the gate region being located on the side of the base region remote from said first major surface, the thickness of the base region between the first and second p-n junctions being more than 25 microns, that region of the anode and cathode regions which is of the same conductivity type as the base region extending closer to the gate region than the other of the anode and cathode regions, and a first recess in said first major surface laterally separating the anode and cathode regions and extending through the base region towards said second p-n junction so that the depletion layer from the biased second p-n junction can extend to said first recess to interrupt the current path.