Abstract: The invention proposes a bipolar transistor comprising a substrate, emitter, base, and collector layers and, if appropriate, contact layers. The base layer is formed from a GaAsSb material. The transistor also has at least one transition layer formed from a GaInP material between the emitter layer and the base layer. The presence and composition of the transition layer allows the profile of the conduction band of the transistor to be shaped to optimize performance. Further, the composition of the transition layer facilitates fabrication of the transistor by selective etching. The invention also relates to a circuit comprising a bipolar transistor of the invention. The invention also proposes a method of fabricating a transistor in accordance with the invention.

Abstract: A metal-semiconductor-metal photodetector including an absorbent layer, a barrier layer of greater forbidden band energy on which there are deposited Schottky electrodes and a transition layer of graded composition, the photodetector including a doping plane situated in the vicinity of the join between the absorbent layer and the transition layer of graded composition.

Abstract: An avalanche photodiode having an absorption zone, a multiplication zone, and a transition zone disposed between the absorption zone and the multiplication zone, the transition zone being doped and being constituted at least in part by a material of composition that is graded such that the energy bands of the structure are substantially continuous when it is biased, wherein said doping is distributed non-uniformly in said graded composition zone so as to compensate, at least in part, the reverse electric field due to the composition grading of the material in the transition zone.

Abstract: Method for making an integrated guide/detector structure made of a semiconductive material.

Abstract: A phototransistor comprising a substrate (9), a collector layer (2), a base layer (3), and an emitter layer (4) is disclosed. The base layer (3) is of a first composite III-V semiconductor material with a first type of doping and the emitter layer (4) is of a second composite III-V semiconductor material. A diffusion well (6), of the first type of doping extends on a main part of the emitter layer (4) down to the base layer. The remaining part of the emitter layer (4) is of a second type of doping. The main part of the emitter layer (4) has an area at least 100 times larger than the area of the remaining part. A contact layer with the second type of doping is deposited on the remaining part of the emitter layer (4) with an emitter contact on the contact layer, and a base contact on an extremity of the diffusion well (6).