Scr with amplified emitter gate

Claim 2

An improved semiconductor switching device comprising four layers of semiconductor material arranged in succession between first and second main current carrying electrodes, with contiguous layers being of different conductivity types so that rectifying junctions are formed therebetween, a first one of the opposite end layers of semiconductor material comprising laterally adjoining main and auxiliary regions, the former being disposed in relatively broad area contact with the first main electrode and the latter being free of that electrode, said device being adapted to be triggered from a nonconducting state to a main current conducting state by means impinging on said auxiliary region of said first end layer, said triggering means comprising a trigger signal whose magnitude is within a predetermined range, wherein the improvement comprises said auxiliary region having juxtaposed first, second, and third parts: a. said first part extending laterally from a border of said main region, b. said second part being disposed laterally adjacent to said first part in spaced relation to said main region and being the only part of said auxiliary region on which said triggering means impinges; c. said third part being located between said first and second parts; and d. an island of electroconductive material covering said third part of said auxiliary regioN, said island being separate from said second part and remote from said first main electrode; e. said first part of the auxiliary region being thinner than the bordering portions of said third part and of said main region, respectively, and said second part being thinner than any bordering portion of said third part and being so constructed and arranged in relation to said first and third parts that its lateral resistance, measured between said electroconductive material and the center of the area where said triggering means impinges, is higher than the resistance between said first main electrode and said electroconductive material, whereby, upon triggering of the device, main current conduction will always start in a portion thereof under said electroconductive material for any magnitude of trigger signal within said predetermined range.

Claim 3

The device of claim 3 wherein said first and second parts of the auxiliary region are disposed under etched-out recesses in the original exterior surface of said first end layer.

Claim 4

An improved semiconductor switching device comprising a semiconductor body having four layers arranged in succession between first and second main current carrying electrodes, with contiguous layers being of different conductivity types so that rectifying junctions are formed therebetween, a first one of the opposite end layers of said body comprising juxtaposed main and auxiliary regions, the former being disposed in relatively broad area contact with the first main electrode and the latter being free of that electrode, said device being adapted to be triggered from a nonconducting state to a main current conducting state by means impinging on the surface of a predetermined part of a first auxiliary region of said first end layer, said triggering means comprising a trigger signal whose magnitude is within a predetermined range, wherein the improvement comprises: a. a first island of electroconductive material overlaying another part of said first auxiliary region, said other part being spaced from said main region and said first island being remote from said first main electrode; b. a second auxiliary region in said first end layer extending laterally from a border of said main region and being free of said first main electrode; c. a second island of electroconductive material intimately connected to a part of said second auxiliary region spaced from said border, said second island being remote from said first main electrode; d. means for conductively interconnecting said first and second islands; and e. said islands and said auxiliary regions being so constructed and arranged that the lateral resistance of said predetermined part of said first auxiliary region is higher than the resistance between said first main electrode and said islands, whereby, when the device is triggered by a trigger signal of any magnitude in said predetermined range, i. the trigger delay time of the rectifying junction between said other part of the first auxiliary region and a contiguous intermediate layer of said body is shorter than that of the rectifying junction between said main region and said intermediate layer, ii. main current always starts in a path of relatively small area under said first island, flows through said first and second islands and their interconnecting means, and crosses an appreciable length of said border of the main region, and iii. a significant fraction of initial main current will flow through the rectifying junction between said main region and said intermediate layer, thereby acting as a peremptory trigger for the portion of said body subtending said first main electrode.

Claim 5

The device of claim 5 in which the first auxiliary region is located inboard with respect to said main region and said second auxiliary region is located outboard with respect thereto.