An image sensor including a pixel array, each pixel including, in a substrate of a doped semiconductor material of a first conductivity type, a first doped region of a second conductivity type at the surface of the substrate; an insulating trench surrounding the first region; a second doped region of the first conductivity type, more heavily doped than the substrate, at the surface of the substrate and surrounding the trench; a third doped region of the second conductivity type, forming with the substrate a photodiode junction, extending in depth into the substrate under the first and second regions and being connected to the first region; and a fourth region, more lightly doped than the second and third regions, interposed between the second and third regions and in contact with the first region and/or with the third region.