A semiconductor device comprising at least two holes (18, 20) realized in a substrate (6), having each a width and a depth, and forming a diode (4), wherein the substrate (6) has a determined type of doping, wherein the inner wall of each hole (18, 20) is doped so that its doping is of the other type than the doping of the substrate (6), and wherein the width and/or the depth of a hole (18, 20) is different from the width and/or the depth of a neighboring hole.