A photodiode comprises three superposed doped regions, namely a first doped region adjacent to a surface (S) of a semiconductor substrate, an intermediate second doped region and a third doped region in contact with the bulk of the substrate. The bulk of the substrate and the second doped region form first and second electrodes of the photodiode, respectively. The photodiode furthermore includes a third electrode in contact with the first doped region. The third electrode comprises an intermediate portion of a first electrically conducting material, placed in contact with the first doped region, and an external connection portion of a second electrically conducting material, placed in contact with the intermediate portion.