Abstract: An asymmetrical thyristor having an n.sup.+ pn.sup.- np.sup.- zone sequence whose functionability is not impaired and, in particular, whose reverse blocking characteristic is not degraded, if it fires after a forward current load and subsequent commutation before its turn-off time has expired due to the positive voltage increasing again. This insensitivity to refiring after commutation when falling below the turn-off time is realized by a flat rise of the doping concentration from the n.sup.- -type zone to the n-type zone, with the doping concentration in the n-type layer increasing approximately exponentially over a path of at least 50.mu.. In order to keep the forward off-state current low with a flat nn.sup.- junction, the thickness and doping of the n.sup.- -type layer are dimensioned such that at the highest intended forward off-state voltage the electric field intensity at the pn.sup.- junction is about 1.5.multidot.10.sup.5 V/cm, drops approximately linearly in the n.sup.- -type layer and, at the nn.