Quantum well photoelectric detector with improved detectivity

Photoelectric detector presenting a multiple quantum well structure, each quantum well comprising a first barrier made from a first semiconductor material, a well made from a second semiconductor material, and a second barrier made from a third semiconductor material, each semiconductor material being defined by its chemical composition, and the electric conductibility in the detector being ensured by propagation, from the first barrier to the second barrier, of given charge carriers in a given electronic band, presenting an energy extremum in each of the said materials, said semiconductor materials being at least partly doped with carriers, the chemical composition of the first and third semiconductor materials being such that the difference in energy, at the said barriers, between the energy extremum of the said electronic band in the first semiconductor material and the energy extremum of the said electronic band in the third semiconductor material is greater in absolute value than the maximum energy of the optical longitudinal phonons in the second semiconductor material making up the well, said structure being formed from an alternating stack of layers of the second semiconductor material separated by layers of a semiconductor material presenting, from the second barrier of one well to the first barrier of the following well, in the direction of carrier propagation, a chemical composition that gradually varies between the composition of the third semiconductor material to that of the first semiconductor material.