Light emitting and receiving transistor for operation in alternate _sequence in an optical-fiber telecommunications systems
First Claim
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1. A light emitting and receiving transistor comprising:
- a semiconductor substrate and plural semiconductor layers formed in series on said substrate, including,a first layer farthest away from said substrate adapted to be coupled to an entrance face or an exit face of an optical fiber, said first layer having a predetermined wide bandgap composition and being of a first conductivity type,a second layer having a predetermined narrow bandgap composition and being of a second conductivity type opposite that of said first layer formed adjacent said first layer, anda third layer having a predetermined wide bandgap composition and being of said first conductivity type formed adjacent said second layer;
said second layer being an active layer and having an interface with said first layer forming a first pn heterojunction and an interface with said third layer forming a second pn heterojunction;
said first layer having formed in only a part thereof a heavily doped region of the second conductivity type extending through said first layer to said second layer;
wherein said substrate and said layers form a transistor having base, emitter and collector functions, the transistor base function being performed by said active layer while the emitter function is performed by the first layer and the collector function is performed by said substrate, said active layer, said third layer and said second heterojunction forming a light emission region; and
base, emitter, and collector electrodes respectively connected to said heavily doped region formed in said first layer, said first layer, and said substrate.
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Abstract
A phototransistor which is capable of operating alternately in the emission mode and in the reception mode can be coupled under favorable conditions to an optical fiber in a telecommunications system. An active layer constitutes the base of the transistor and forms a heterojunction with two layers of opposite conductivity type which constitute the emitter and collector of the transistor. The base contact is formed by a heavily doped region of the same conductivity type as the active layer and defines the useful zone of photon coupling between the optoelectronic component and the entrance face or exit face of the optical fiber.
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6 Claims
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1. A light emitting and receiving transistor comprising:
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a semiconductor substrate and plural semiconductor layers formed in series on said substrate, including, a first layer farthest away from said substrate adapted to be coupled to an entrance face or an exit face of an optical fiber, said first layer having a predetermined wide bandgap composition and being of a first conductivity type, a second layer having a predetermined narrow bandgap composition and being of a second conductivity type opposite that of said first layer formed adjacent said first layer, and a third layer having a predetermined wide bandgap composition and being of said first conductivity type formed adjacent said second layer; said second layer being an active layer and having an interface with said first layer forming a first pn heterojunction and an interface with said third layer forming a second pn heterojunction; said first layer having formed in only a part thereof a heavily doped region of the second conductivity type extending through said first layer to said second layer; wherein said substrate and said layers form a transistor having base, emitter and collector functions, the transistor base function being performed by said active layer while the emitter function is performed by the first layer and the collector function is performed by said substrate, said active layer, said third layer and said second heterojunction forming a light emission region; and base, emitter, and collector electrodes respectively connected to said heavily doped region formed in said first layer, said first layer, and said substrate. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification