Photodetecting device comprising: a semiconductor layer doped according to a first type of conductivity; two first semiconductor portions doped according to a second type of conductivity opposed to the first type of conductivity, distinct and separated from one another, and arranged in the semiconductor layer next to one another; a second semiconductor portion doped according to the first type of conductivity with a level of doping greater than that of the semiconductor layer and delimiting, with the semiconductor layer, the first portions by forming p-n junctions, wherein a part of the semiconductor layer separates the first portions such that the depletion zones between the first portions form a potential barrier of which the level is less than the potential of the second portion and of the semiconductor layer.