Abstract: A semiconductor device comprises means (7) for grading an electric field created in the active part (4) of the device when a high voltage is applied thereacross. Said means comprises a member (7) being of a material having a higher dielectric constant than the material of said active part and applied next to at least a portion of said active part where a high electric field occurs when a high voltage is applied across the device for obtaining a field grading for a condition of changing of said voltage.

Abstract: An electric switching device comprises a quick mechanical electric switch and an irradiation source and at least one switching element sensitive to irradiation and adapted to create an electrically well conducting current path by-passing the electric mechanical switch upon irradiation thereon through the irradiation source, but assuming an electrically insulating state in absence of irradiation thereon. The quick mechanical electric switch is capable of being quickly de-ionized after extinction of an electric arc created therein upon separation of the contacts of the mechanical switch.

Abstract: A switch comprises at least a first layer of a first material and two contact electrodes arranged on opposite sides of the first layer and connectable to different potentials for applying a voltage thereacross. A first layer is adapted to be conducting upon applying a voltage across the contact electrodes when exposed to irradiation through an irradiation source of an energy high enough for lifting charge carriers from the valence band to the conduction band of the first material. The contact electrode arranged on the first side of the first layer is laterally displaced with respect to the contact electrode arranged on the opposite second side of the layer with a lateral distance separating them.

Abstract: A photoconductive switch, having at least a part of a first layer doped with dopants providing substantially no free charge carriers for charge transport between the electrodes at the normal operation temperature of the switch, has the nature of the doping, i.e., concentration, type (n or p). The dopants, varied from the first side to an opposite, second side of the first layer for co-operating with the intensity distribution of the light emitted by an illumination source, strikes the first side versus energy so as to obtain a substantially even creation of free charge carriers throughout the depth of the first layer from the first to the second side when illuminated by the illumination source.